Current sensing devices and methods

ABSTRACT

A low-cost and high-precision current sensing device and methods for use and manufacturing. In one embodiment, the current sensing apparatus comprises a Rogowski-type coil which is manufactured in segments so as to facilitate the manufacturing process. In an exemplary embodiment, the current sensing apparatus segments comprise a number of bobbin elements that are wound and subsequently formed into complex geometric shapes such as torus-like shapes. In an alternative embodiment, bonded windings are utilized which allow the segments to be formed without a bobbin or former. In yet another alternative embodiment, the aforementioned current sensing devices are stacked in groups of two or more. Methods of manufacturing and using the aforementioned current sensing apparatus are also disclosed.

PRIORITY

This application is a continuation-in-part of and claims priority toU.S. patent application Ser. No. 12/684,056 filed Jan. 7, 2010 of thesame title, which is a continuation-in-part of and claims priority toU.S. patent application Ser. No. 12/567,622 filed Sep. 25, 2009 of thesame title, which claims priority to U.S. Provisional Patent ApplicationSer. No. 61/230,474 filed Jul. 31, 2009 of the same title, each of whichis incorporated herein by reference in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

1. FIELD OF THE INVENTION

The present invention relates generally to circuit elements and moreparticularly in one exemplary aspect to devices for the sensing ofcurrent, and methods of utilizing and manufacturing the same.

2. DESCRIPTION OF RELATED TECHNOLOGY

A myriad of different configurations of current sensing devices areknown in the prior art. One common approach to the manufacture ofcurrent sensing devices is via the use of a so-called “Rogowski coil”. ARogowski coil is an electrical device for measuring alternating current(“AC”). It typically consists of a helical coil of wire with the leadfrom one end returning through the center of the coil and passingthrough the helical coil of wire to the other end. The whole helicalcoil of wire is then positioned around an alternate current carryingconductor whose current is to be measured. The voltage that is inducedin the coil is proportional to the rate of change of current in theconductor such that the output of the Rogowski coil is indicative to theamount of current passing through the conductor.

Rogowski coils can be made open-ended and flexible, allowing it to bewrapped around a current carrying conductor without otherwise directlydisturbing the current passing through that conductor. A Rogowski coiltypically utilizes air, rather than a magnetically permeable coretherefore giving the Rogowski coil the properties of possessing both arelatively low inductance along with response to relativelyfast-changing currents. Furthermore, the output of a Rogowski coil istypically highly linear, even when subjected to large currents such asthose used in electric power transmission, welding, or other pulsedpower applications. In addition, properly constructed Rogowski coils areoften also largely immune to electromagnetic interference, therebymaking them resistant to outside tampering. However, due to therelatively complex winding configurations involved, prior art attemptsat manufacturing Rogowski type coils have been labor intensive andexpensive.

Numerous methodologies exist for producing Rogowski coils in the priorart, including for example, those disclosed in U.S. Pat. No. 4,616,176to Mercure, et al. issued Oct. 7, 1986 and entitled “Dynamic currenttransducer”; U.S. Pat. No. 5,414,400 to Gris, et al. issued. May 9, 1995and entitled “Rogowski coil”; U.S. Pat. No. 5,442,280 to Baudart issuedAug. 15, 1995 and entitled “Device for measuring an electrical currentin a conductor using a Rogowski coil”; U.S. Pat. No. 5,982,265 to VonSkarczinski, et al. issued Nov. 9, 1999 and entitled “Current-detectioncoil for a current transformer”; U.S. Pat. No. 6,094,044 to Kustera, etal. issued Jul. 25, 2000 and entitled “AC current sensor having highaccuracy and large bandwidth”; U.S. Pat. No. 6,313,623 to Kojovic, etal. issued Nov. 6, 2001 and entitled “High precision Rogowski coil”;U.S. Pat. No. 6,614,218 to Ray issued Sep. 2, 2003 and entitled “Currentmeasuring device”; U.S. Pat. No. 6,731,193 to Meier, et al. issued May4, 2004 and entitled “Printed circuit board-based current sensor”; U.S.Pat. No. 6,822,547 to Saito, et al. issued Nov. 23, 2004 and entitled“Current transformer”; U.S. Pat. No. 7,227,441 to Skendzic, et al.issued Jun. 5, 2007 and entitled “Precision Rogowski coil and method formanufacturing same”; U.S. Pat. No. 7,253,603 to Kovanko, et al. issuedAug. 7, 2007 and entitled “Current sensor arrangement”; U.S. Pat. No.7,538,541 to Kojovic issued May 26, 2009 and entitled “Split Rogowskicoil current measuring device and methods”; United States Patent Pub.No. 20050248430 to Dupraz, et al. published Nov. 10, 2005 and entitled“Current transformer with Rogowski type windings comprising anassociation of partial circuits forming a complete circuit”; UnitedStates Patent Pub. No. 20060220774 to Skendzic published Oct. 5, 2006and entitled “Precision printed circuit board based Rogowski coil andmethod for manufacturing same”; United States Patent Pub. No.20070290695 to Mahon published Dec. 20, 2007 and entitled “Method andApparatus for Measuring Current”; United States Patent Pub. No.20080007249 to Wilkerson; et al. published Jan. 10, 2008 and entitled“Precision, Temperature-compensated, shielded current measurementdevice”; United States Patent Pub. No. 20080079418 to Rea; et al.published Apr. 3, 2008 and entitled “High-precision Rogowski currenttransformer”; United States Patent Pub. No. 20080106253 to Kojovicpublished May 8, 2008 and entitled “Shielded Rogowski coil assembly andmethods”; and United States Patent Pub. No. 20080211484 to HOWELL; etal. published Sep. 4, 2008 and entitled “Flexible current transformerassembly”.

Despite the broad variety of prior art current sensing configurations,there is a salient need for current sensing devices (including Rogowskicoils) that both are low in cost to manufacture, such low cost beingenabled by inter glia addressing the difficulties associated with thecomplex coil configurations of prior art current sensing devices, andoffer improved or at least comparable electrical performance over priorart devices. Ideally such a solution would not only offer very lowmanufacturing cost and improved electrical performance for the currentsensing device, but also provide a high level of consistency andreliability of performance by limiting opportunities for errors or otherimperfections during manufacture of the device.

Moreover, an ideal solution would also be at least somewhat scalable,and able to assume various desired form factors.

SUMMARY OF THE INVENTION

In a first aspect of the invention, an improved current sensinginductive device is disclosed. In one embodiment, the current sensinginductive device includes multiple ones of segmented winding elements. Areturn conductor electrically couples a leading one of the segmentedwinding elements with a trailing one of the segmented winding elements.

In one embodiment, the segmented winding elements comprise segmentedbobbin elements upon which a number of windings are disposed.

In another embodiment, the windings are effectively free-standing suchthat no bobbin or other internal support structure is required.

In a second aspect of the invention, an improved form-less currentsensing inductive device is disclosed. In one embodiment, the inductivedevice includes multiple ones of form-less wound air coils. These aircoils are then placed within respective cavities located on anencapsulating header. A return conductor couples a leading one of theform-less coils with a trailing one of the form-less coils.

In a third aspect of the invention, a system apparatus that incorporatesthe aforementioned current sensing inductive devices is disclosed. Inone embodiment, the system apparatus comprises a power distributionutility box that incorporates an improved current sensing inductivedevice. The power distribution utility box includes a network interfacethat transmits data collected by the current sensing inductive deviceover a network to a device or location (e.g., centralized repository orcontrol center) for monitoring, billing, and/or control applications.

In a fourth aspect of the invention, methods of manufacturing theaforementioned device(s) are disclosed. In one embodiment, the methodcomprises continuously winding an insulated conductor over multiplesegmented bobbin elements. A return conductor is routed between each ofthe segmented bobbin elements. The return conductor is then electricallycoupled with the insulated conductor so as to form the current sensinginductive device.

In a fifth aspect of the invention, methods of using the aforementionedapparatus are disclosed.

In a sixth aspect of the invention, a scalable inductive device isdisclosed. In one embodiment, the device comprises a number of windingsegments, and the number of winding segments (and/or number of turns persegment) can be varied as desired so as to achieve a desired tradeoffbetween higher performance and higher cost of manufacturing.

In a seventh aspect of the invention, a low cost and highly preciseinductive device is disclosed. In one embodiment, a number of segmentsare used to effectively approximate a circular, continuous Rogowski coildevice.

In an eighth aspect of the invention, a user-tunable multi-coil assemblyis disclosed. In one embodiment, two or more segmented coils are stacked(i.e., in juxtaposed disposition with a common central axis), such thatthe angular disposition (rotation) of the coils around the common axiscan be varied by an installer or end user, and/or the number of coilspresent can be changed. As the segments of one coil are placed indifferent position with respect to the segments of the other coil(s)(and/or the number of coils increased or decreased), the output of thedevices will vary, thereby allowing the installer/user to “tune” theeffective output of the coil assembly to the desired level ofperformance.

In another embodiment, the two or more coils are substantiallyconcentric with one another, such that they have different radii.Similarly, when the relative position of the coils is changed (and/ornumber of coils varied), the output of the coils will vary as well, andcan be tuned or adjusted to a desired level of performance.

Moreover, in yet another embodiment, the vertical spacing or dispositionof the different coils (whether in “stacked” or “concentric”configuration) can be varied, thereby increasing/decreasing the couplingor interaction of the coils.

In a ninth aspect of the invention, a coil device having a conductorreceiving insert is disclosed. In one embodiment, the device comprises asegmented coil of the type referenced above, which further includes acentral portion adapted to orient and place one or more conductors beingmonitored at a prescribed location within the center region of the coil.

In a tenth aspect of the invention, a support structure for use with theaforementioned current sensing inductive devices is disclosed. In onembodiment, the support structure includes multiple ones of bobbinelements. At least a portion of the bobbin elements also includeconnection features that are utilized for joining a bobbin element to anadjacent bobbin element.

In an eleventh aspect of the invention, a bobbin element for use in theaforementioned current sensing inductive devices is disclosed. In oneembodiment, the bobbin element includes a spool element which defines aninterior volume and further having an outer winding diameter associatedwith the spool element. A pair of flange features is also disposed onopposing ends of the spool element.

In a variant, at least one of the pair of flange features includes anelectrically conductive clip disposed therein.

In yet another variant, the interior volume includes a return conductorsupport feature that positions a return conductor at a predeterminedposition with respect to the spool element.

In a twelfth aspect of the invention, a current sensing inductive deviceis disclosed. In one embodiment the device comprises: a plurality ofbobbin elements, each element having one or more terminals with aconductive winding wound thereon; and a printed circuit board with anaperture existing therein. The plurality of bobbin elements are disposedabout the aperture and are electrically coupled to one another via theprinted circuit board.

In one variant, the device further comprises: a return conductor thatelectrically couples a leading one of the plurality of bobbin elementswith a trailing one of the bobbin elements.

In another variant, at least two of the plurality of bobbin elements arephysically coupled to one another via a hinged coupling.

In yet another variant, at least three of the plurality of bobbinelements are physically coupled to one another via one or more of aplurality of hinged couplings, respectively, with a first hingedcoupling disposed on a first side of a winding channel of a first bobbinelement, and a second hinged coupling disposed on a second side of thewinding channel of the first bobbin element.

In a further variant, each of the bobbin elements comprises a pair offlanges with a winding spool disposed substantially therebetween, theconductive winding wound onto the winding spool. The one or moreterminals comprise e.g., self-leaded terminals incorporated into atleast a sidewall of at least one of the pair of flanges.

In still another variant, the plurality of bobbin elements comprisesthree or more bobbin elements, with a start and a finish portion of theconductive winding being disposed on a non-end one of the three or morebobbin elements.

In a further variant, the conductive winding comprises a pluralitylayers disposed on one or more winding barrels of the bobbin elements,and at least one of the layers comprises a shielding layer operative tomitigate the effects of an external electromagnetic field.

In another variant, the plurality of layers comprises: two or moreshielding layers; and two or more current sensing layers. The two ormore shielding layers and the two or more current sensing layers areinterleaved with one another.

In another embodiment, the current sensing inductive device comprises: aplurality of linearly wound inductive elements, each element comprising:a pair of flanges; a winding channel disposed between the pair offlanges; a plurality of layers of conductive winding disposed in thewinding channel; and one or more hinge features; and a housingcomprising a conductor receiving aperture. The plurality of linearlywound inductive elements are collectively disposed about the conductorreceiving aperture in a substantially alternating or zigzag fashion.

In one variant, at least one of the plurality of layers of windingscomprises a shielding layer, and the direction of winding for theshielding layer alternates between adjacently disposed linearly woundinductive devices.

In another variant, the conductor receiving aperture includes anintegrated conductor that is to be sensed by the linearly woundinductive elements.

In a further variant, the housing further comprises a plurality ofterminals for electrically interfacing with a printed circuit board.

In still another variant, the housing includes a plurality of alignmentfeatures that arrange the linearly wound inductive elements in thealternating or zigzag fashion when the linearly wound inductive elementsare received therein.

In a thirteenth aspect of the invention, a method of manufacturing acurrent sensing inductive device is disclosed. In one embodiment, themethod comprises: securing a first end of a conductive winding to one ofa plurality of segmented winding elements; continuously winding theconductive winding onto the plurality of segmented winding elements in asequential order; and securing the second end of the conductive windingto one of the plurality of segmented winding elements.

In one variant, the first end and the second end of the securedconductive winding is secured to the same one of the plurality ofsegmented winding elements. The sequential order comprises for example:traversing from a middle one of the plurality of segmented windingelements to a first end segmented winding element of the plurality ofsegmented winding elements; traversing from the first end segmentedwinding element of the plurality of segmented winding elements to asecond end segmented winding element of the plurality of segmentedwinding elements; and traversing from the second end segmented windingelement of the plurality of segmented winding elements back to themiddle one of the plurality of segmented winding elements.

In another variant, the act of securing the first end comprisesterminating the conductive winding onto a self-leaded terminal presenton the one of the plurality of segmented winding elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objectives, and advantages of the invention will becomemore apparent from the detailed description set forth below when takenin conjunction with the drawings, wherein:

FIG. 1 is a perspective view illustrating a first embodiment of aRogowski coil device in accordance with the principles of the presentinvention.

FIG. 1A is a perspective view illustrating the Rogowski coil header ofFIG. 1 in accordance with the principles of the present invention.

FIG. 1B is a perspective sectional view taken along line 1B-1B of FIG.1A.

FIG. 1C is a perspective view illustrating a Rogowski coil formed by thesegmented or continuous application of an adhesive in accordance withthe principles of the present invention.

FIG. 1D is a top elevation view illustrating a field installableRogowski coil device with overlapping conductor ends in accordance withthe principles of the Rogowski coil.

FIG. 1E is a top elevation view illustrating a field installableRogowski coil device with abutting conductor ends in accordance with theprinciples of the Rogowski coil.

FIG. 2 is a perspective view illustrating a portion of a secondembodiment of a Rogowski coil device in accordance with the principlesof the present invention.

FIG. 2A is a perspective sectional view taken along line 2A-2A of FIG.2.

FIG. 2B is a perspective view of a single Rogowski coil segment, asillustrated in FIG. 2, in accordance with the principles of the presentinvention.

FIG. 2C is a perspective view of the single Rogowski coil segmentillustrated in FIG. 2B, shown from a different perspective.

FIG. 3 is a perspective view illustrating a single Rogowski coil segmentfor a third embodiment of a Rogowski coil device in accordance with theprinciples of the present invention.

FIG. 3A is a side elevation view of the Rogowski coil segmentillustrated in FIG. 3. FIG. 3B is a perspective view illustrating four(4) assembled Rogowski coil segments, as illustrated in FIG. 3, formingone-half of a Rogowski coil device in accordance with the principles ofthe present invention.

FIG. 3C is a perspective view illustrating the four (4) assembledRogowski coil segments of FIG. 3B mounted on a winding mandrel inaccordance with the principles of the present invention.

FIG. 3D is a side elevation view of the winding mandrel mounted Rogowskicoil segments shown in FIG. 3C.

FIG. 4 is a perspective view illustrating a single Rogowski coil segmentfor a fourth embodiment of a Rogowski coil device in accordance with theprinciples of the present invention.

FIG. 4A is a perspective view illustrating two wound Rogowski coilsegments, as illustrated in FIG. 4, mounted between two header segmentsin accordance with the principles of the present invention.

FIG. 4B is a perspective view illustrating eight (8) assembled Rogowskicoil segments of FIG. 4 mounted on a winding mandrel in accordance withthe principles of the present invention.

FIG. 5 is a perspective view illustrating a single Rogowski coil segmentfor a fifth embodiment of a Rogowski coil device in accordance with theprinciples of the present invention.

FIG. 5A is a side elevation view illustrating the single Rogowski coilelement of FIG. 5.

FIG. 5B is a perspective view illustrating two Rogowski coil segments ofFIG. 5 mountable together in accordance with the principles of thepresent invention.

FIG. 5C is a perspective view illustrating eight (8) assembled Rogowskicoil segments of FIG. 5 mounted on a winding mandrel in accordance withthe principles of the present invention.

FIG. 6 is a perspective view illustrating a single Rogowski coil segmentfor a sixth embodiment of a Rogowski coil device in accordance with theprinciples of the present invention.

FIG. 6A is a side elevation view illustrating the single Rogowski coilelement of FIG. 6.

FIG. 6B is a perspective view illustrating two Rogowski coil segments ofFIG. 6 mountable together in accordance with the principles of thepresent invention.

FIG. 6C is a perspective view illustrating another embodiment of a coilsegment adapted to receive a peripheral cord, in accordance with theprinciples of the present invention.

FIG. 7 is a side elevation view illustrating various positions for thepass through conductor of a current sensing device in accordance withthe principles of the present invention.

FIG. 8 is a top elevation view illustrating an alternate configurationfor a Rogowski coil device positioned about a rectangular powerconductor in accordance with the principles of the present invention.

FIG. 8A is a top elevation view illustrating a first exemplaryembodiment of the Rogowski coil device of FIG. 8 with alignment featuresincorporated thereon to prevent skewing and biasing in accordance withthe principles of the present invention.

FIG. 8B is a top elevation view of another embodiment of the sensingdevice of the invention, adapted for use on a 4-sided (e.g.,rectangular) bus bar (with cover removed).

FIG. 8B-1 is a cross-section of the device of FIG. 8B, taken along line8B-1-8B-1, with cover installed.

FIG. 9 is a side elevation view illustrating an alternate configurationfor a Rogowski coil device in accordance with the principles of thepresent invention.

FIG. 10 is a process flow diagram for manufacturing the current sensingapparatus of FIGS. 1-1B in accordance with the principles of the presentinvention.

FIG. 11 is a process flow diagram for manufacturing the current sensingapparatus of FIGS. 2-2C and FIGS. 4-4B in accordance with the principlesof the present invention.

FIG. 12 is a process flow diagram for manufacturing the current sensingapparatus of FIGS. 3-3D in accordance with the principles of the presentinvention.

FIG. 13 is a process flow diagram for manufacturing the current sensingapparatus of FIGS. 5-5C in accordance with the principles of the presentinvention.

FIG. 14 is a process flow diagram for manufacturing the current sensingapparatus of FIGS. 6-6B in accordance with the principles of the presentinvention.

FIG. 15A is a perspective view of an exemplary stacked Rogowski coildevice in accordance with the principles of the present invention.

FIG. 15B is a top elevation view of the stacked Rogowski coil device ofFIG. 15A.

FIG. 15C is a perspective view of a tunable implementation of thestacked Rogowski coil device of FIG. 15A.

FIG. 15D is a perspective section view of a second exemplary embodimentof a tunable stacked Rogowski coil device in accordance with theprinciples of the present invention.

FIG. 15E is a top elevation view of a concentrically stacked Rogowskicoil device in accordance with the principles of the present invention.

FIG. 16 is a perspective view illustrating a portion of a seventhembodiment of a Rogowski coil segment in accordance with the principlesof the present invention.

FIG. 16A is a perspective view illustrating the Rogowski coil segment ofFIG. 16, linked together with other like segments to form a Rogowskicoil device.

FIG. 16B is a perspective view of an exploded view of the seventhembodiment of a Rogowski coil device and housing.

FIG. 16C is a sectional view taken along line 16C-16C of FIG. 16B.

FIG. 16D is a top elevation view of the bottom housing portionassociated with the Rogowski coil device illustrated in FIG. 16B.

FIG. 17 is a perspective view illustrating an eighth embodiment of aRogowski coil segment in accordance with the principles of the presentinvention.

FIG. 17A is a perspective view illustrating the Rogowski coil segment ofFIG. 17 linked together with other like segments to form a Rogowski coildevice.

FIG. 17B is a sectional view taken along line 17B-17B of FIG. 17A.

FIG. 18A is a perspective view illustrating the insertion of the startclip for a Rogowski coil segment in accordance with one embodiment ofthe present invention.

FIG. 18B is a perspective view illustrating the insertion of the endclip for a Rogowski coil segment in accordance with one embodiment ofthe present invention.

FIG. 18C is a perspective view illustrating the insertion of theRogowski coil segments onto a winding mandrel in accordance with oneembodiment of the present invention.

FIG. 18D is a perspective view illustrating the installation of the coreassembly into the bobbin segment grooves in accordance with oneembodiment of the present invention.

FIG. 18E is a perspective view illustrating the start of one embodimentof the winding process in accordance with the principles of the presentinvention.

FIG. 18F is a cross sectional view illustrating layered windingsdisposed on the first Rogowski coil segment in accordance with oneembodiment of the present invention.

FIG. 18G is a perspective view illustrating the passage of the windingbetween Rogowski coil segments in accordance with one embodiment of thepresent invention.

FIG. 18H is a perspective view of the Rogowski coil segments mounted onthe winding mandrel and wound in accordance with one embodiment of thepresent invention.

FIG. 18I is a perspective view illustrating the termination of thewinding to the start clip in accordance with one embodiment of thepresent invention.

FIG. 18J is a cross sectional view illustrating the shielding layerwindings on a first Rogowski coil segment in accordance with oneembodiment of the present invention.

FIG. 18K is a perspective view of the Rogowski coil segments mounted onthe winding mandrel and wound with the shielding layer in accordancewith one embodiment of the present invention.

FIG. 18L is a perspective view illustrating the winding of a tape layerover the shielding layer of windings in accordance with one embodimentof the present invention.

FIG. 18M is a perspective view illustrating the termination of thewindings to the end clip in accordance with one embodiment of thepresent invention.

FIG. 18N is a perspective view illustrating the insertion of the returnconductor in accordance with one embodiment of the present invention.

FIG. 18O is a perspective view illustrating the insertion of the finishwire conductor in accordance with one embodiment of the presentinvention.

FIG. 18P is a top elevation view illustrating the insertion of theRogowski coil segments into the header in accordance with one embodimentof the present invention.

FIG. 18Q is a perspective view illustrating the installation of the wireconductors in the Rogowski header in accordance with one embodiment ofthe present invention.

FIG. 18R is a perspective view illustrating the deposit of epoxy intothe top header of the Rogowski device in accordance with one embodimentof the present invention.

FIG. 18S is a perspective view illustrating the Rogowski coil devicemanufactured using the process illustrated in FIGS. 18A-18R.

FIG. 19A is a perspective view of a surface mountable bobbin element foruse in a Rogowski coil device in accordance with an embodiment of theinvention.

FIG. 19B is a top view of an exemplary Rogowski coil device thatutilizes the surface mountable bobbin elements of FIG. 19A.

FIG. 19C is a perspective view of the Rogowski coil device illustratedin FIG. 19B.

FIG. 20A is a perspective view of a surface mountable coil assembly inaccordance with another embodiment of the present invention.

FIG. 20B is a perspective view of the surface mountable coil assembly ofFIG. 20A showing the hinged nature of the individual bobbin elements.

FIG. 21 is a perspective view of a Rogowski coil device utilizing twosubstrates and the surface mountable bobbin elements of FIG. 19A.

FIG. 22 is a perspective view of a dual hinged bobbin assembly inaccordance with an embodiment of the present invention.

FIG. 23A is a top view of a first embodiment of a “zigzag” bobbinarrangement disposed about a bus bar in accordance with the principlesof the present invention.

FIG. 23B is a top view of a second embodiment of a zigzag bobbinarrangement disposed about a bus bar in accordance with an embodiment ofthe present invention.

FIG. 24 is a top view of a closed loop zigzag bobbin Rogowski coildevice in accordance with an embodiment of the present invention.

FIG. 25A is a top view of a first embodiment of a non-closed loop sensorand bobbin arrangement in accordance with an embodiment of the presentinvention.

FIG. 25B is a top view of a second embodiment of a non-closed loopsensor and bobbin arrangement in accordance with an embodiment of thepresent invention.

FIG. 26 is a perspective view of a Rogowski coil device with anintegrated bus bar in accordance with an embodiment of the presentinvention.

FIG. 27A is a perspective view of a surface mountable Rogowski coildevice in accordance with an embodiment of the present invention.

FIG. 27B is a perspective view of the surface mountable Rogowski coildevice of FIG. 27A mounted onto a substrate.

FIG. 28 is a top view of a multiple sensor module with built-incrosstalk compensation in accordance with an embodiment of the presentinvention.

FIG. 29A is a process flow diagram illustrating a first exemplaryRogowski coil device winding technique with the lead outs positioned ona center bobbin in accordance with an embodiment of the presentinvention.

FIG. 29B is a process flow diagram illustrating a second exemplaryRogowski coil device winding technique with the lead outs positioned ona center bobbin in accordance with an embodiment of the presentinvention.

FIG. 30 is a front view of a bank winding configuration in accordancewith an embodiment of the present invention.

FIG. 31 is a process flow diagram illustrating an alternating directionshield winding in accordance with the principles of the presentinvention.

FIG. 32 is a cross sectional view illustrating interleaved shieldedwindings disposed on the first Rogowski coil segment in accordance withone embodiment of the present invention.

FIG. 33 is a top view illustrating shielding of individual bobbinsegments in accordance with an embodiment of the present invention.

FIG. 34 is a top view illustrating shielding on the inner diameter of acurrent sensor in accordance with an embodiment of the presentinvention.

FIG. 35A is a perspective view of a first embodiment of a circuit boardmounted multi-coil current sensing apparatus in accordance an embodimentof the present invention.

FIG. 35B is a perspective view of a second embodiment of a circuit boardmounted multi-coil current sensing apparatus in accordance with anembodiment of the present invention.

FIG. 35C is a process flow diagram illustrating an alternative windingconfiguration for the multi-coil current sensing apparatus of FIG. 35Aor 35B.

All Figures disclosed herein are © Copyright 2009-2010 PulseEngineering, Inc. All rights reserved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference is now made to the drawings wherein like numerals refer tolike parts throughout.

As used herein, the terms “bobbin” and “form” (or “former”) are usedwithout limitation to refer to any structure or component(s) disposed onor within or as part of an inductive device which helps form or maintainone or more windings of the device.

As used herein, the terms “electrical component” and “electroniccomponent” are used interchangeably and refer to components adapted toprovide some electrical and/or signal conditioning function, includingwithout limitation inductive reactors (“choke coils”), transformers,filters, transistors, gapped core torpids, inductors (coupled orotherwise), capacitors, resistors, operational amplifiers, and diodes,whether discrete components or integrated circuits, whether alone or incombination.

As used herein, the term “inductive device” refers to any device usingor implementing induction including, without limitation, inductors,transformers, and inductive reactors (or “choke coils”.

As used herein, the terms “network” and “bearer network” refer generallyto any type of data, telecommunications or other network including,without limitation, data networks (including MANs, PANs, WANs, LANs,WLANs, micronets, piconets, internets, and intranets), hybrid fiber coax(HFC) networks, satellite networks, cellular networks, and telconetworks. Such networks or portions thereof may utilize any one or moredifferent topologies (e.g., ring, bus, star, loop, etc.), transmissionmedia (e.g., wired/RF cable, RF wireless, millimeter wave, optical,etc.) and/or communications or networking protocols (e.g., SONET,DOCSIS, IEEE Std. 802.3, 802.11, ATM, X.25, Frame Relay, 3GPP, 3GPP2,WAP, SIP, UDP, FTP, RTP/RTCP, H.323, etc.).

As used herein, the terms “network interface” or “interface” typicallyrefer to any signal, data, or software interface with a component,network or process including, without limitation, those of the FireWire(e.g., FW400, FW800, etc.), USB (e.g., USB2, USB 3.0, USB On-the-Go,etc.), Ethernet (e.g., 10/100, 10/100/1000 (Gigabit Ethernet), 10-Gig-E,etc.), MoCA, optical (e.g., PON, DWDM, etc.), Serial ATA (e.g., SATA,e-SATA, SATAII), Ultra-ATA/DMA, Coaxsys (e.g., TVnet™), radio frequencytuner (e.g., in-band or OOB, cable modem, etc.), WiFi (802.11a,b,g,n),WiMAX (802.16), PAN (802.15), IrDA, or other wireless families.

As used herein, the term “signal conditioning” or “conditioning” shallbe understood to include, but not be limited to, signal voltagetransformation, filtering and noise mitigation, signal splitting,impedance control and correction, current limiting, capacitance control,and time delay.

As used herein, the terms “top”, “bottom”, “side”, “up”, “down” and thelike merely connote a relative position or geometry of one component toanother, and in no way connote an absolute frame of reference or anyrequired orientation. For example, a “top” portion of a component mayactually reside below a “bottom” portion when the component is mountedto another device (e.g., to the underside of a PCB).

As used herein, the term “wireless” means any wireless signal, data,communication, or other interface including without limitation Wi-Fi,Bluetooth, 3G (e.g., 3GPP, 3GPP2, and UMTS), HSDPA/HSUPA, TDMA, CDMA(e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX(802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, analog cellular, CDPD,satellite systems, millimeter wave or microwave systems, optical,acoustic, and infrared (i.e., IrDA).

Overview

The present invention provides, inter glia, improved low cost currentsensing apparatus and methods for manufacturing, and utilizing the same.In one embodiment, the current sensing apparatus are formed in segmentsthat are, in exemplary embodiments, generally linear in nature so as tofacilitate the winding of the apparatus. The formed segments aresubsequently positioned into complex geometries, such as circular,polygonal, or elliptical torus/toroidal like geometries. While torusgeometries are common, the formed segments can be adapted for use with awide variety of geometries in which the conductors they are formedaround are irregular in nature. In addition to substantially fixedforms, additional embodiments disclosed herein are also suitable forflexible assemblies.

The aforementioned “segmented” coil approach advantageously allows forthe control of cost of manufacturing the device to be balanced againstthe required performance or precision level. As greater precision isrequired for a given application, a greater number of segments (and/orgreater number of turns per segment) can be employed, which alsogenerally corresponds to greater cost of manufacture. In low-precisionapplications, a lower-precision device with fewer segments and/or turnscan be utilized, thereby providing the lowest possible cost for therequired level of precision.

In one exemplary implementation, the segments are formed from bobbinelements with features and/or geometries that advantageously facilitatetheir assembly into the final completed current sensing apparatus. Thesebobbin elements include one or more of hinged couplings, alignmentfeatures, molded flexible webbing, etc. in order to facilitate assembly.In an alternative embodiment, the segments are formed fromself-supporting bonded wire windings which are subsequently placed intoa protective header element. One or more return conductor(s) or passthrough conductor(s) is/are also utilized which is electrically coupledto the windings to form the current sensing apparatus.

In addition, some embodiments disclosed herein include an insert-moldedor post-inserted conductive clip which may be utilized not only for wirewrapping (i.e., in order to secure the windings prior to being woundonto the bobbin elements), but also for electrically coupling externallead wires to the bobbin element windings, thus facilitating theelectrical connections needed to form a Rogowski coil device. Bossesformed on the outer flanges of the bobbin elements are also disclosedfor use in some embodiments. These bosses are included withcorresponding paired holes to provide alignment and stability duringwinding operations.

In exemplary embodiments of the device, the header and/or bobbinelements are formed with features that are advantageously incorporatedinto the geometry of the device so as to support and accurately positionthe return conductor(s) with respect to the windings on the device. Thepositioning of the return conductor can be weighed against bothperformance considerations and manufacturing considerations in order toprovide a high performance and low-cost current sensing apparatus. Thepositioning of the conductor can even be variable in nature; e.g.,through a structure which supports multiple different positions of theconductor(s).

“Free space” or “formless” embodiments of the device are also disclosed,wherein the turns of the winding(s) (and the segments themselves) areformed and used without a bobbin or other supporting structure. In onevariant, so-called “bonded” wire is used, wherein the individual turnsof the winding are selectively bonded to one another (e.g., via athermally activated adhesive or other substance) so as to maintain theturns in a desired position and orientation relative to one another,thereby obviating the bobbin and reducing manufacturing cost. In anothervariant, the windings (and center conductor) are encapsulated in apolymer or other encapsulating compound which “pots” the windings andconductor in relative position, and adds mechanical stability andrigidity.

Self-leaded embodiments are also disclosed which utilize, for example,surface mount terminations that allow each of the segments to be bonded(electrically and mechanically) to an underlying circuit board.

“Tunable” embodiments are also envisioned that place two (2) or more ofthe aforementioned current sensing apparatus adjacent to one another inorder to correct for segment-related electrical performancedeficiencies, and/or allow for selective tuning of the coil performanceby a user or installer. In one embodiment, two or more coils arearranged in a stacked or juxtaposed orientation, and placed relative toone another so as to cancel out or mitigate flux leakage associated withthe gaps between coil segments. In another variant, the two or morecoils are substantially concentric.

“Open” embodiments (i.e., those which do not form a closed structure)are also disclosed.

Furthermore, various device packaging options (such as packaging optionswhich included integrated bus bar connections) as well as variouswinding and shielding configurations that can be utilized with variousembodiments of the segmented bobbin and bobbin assemblies describedherein are also described.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Detailed descriptions of the various embodiments and variants of theapparatus and methods of the invention are now provided. While primarilydiscussed in the context of current sensing devices, and in particularin one embodiment to current sensing devices that operate according tothe Rogowski principle, the various apparatus and methodologiesdiscussed herein are not so limited. In fact, many of the apparatus andmethodologies described herein are useful in the manufacture of anynumber of complex coil configurations (such as wound torus shapes) thatcan benefit from the segmented manufacturing methodologies and apparatusdescribed herein, including devices that do not utilize or need a passthrough or return conductor.

In addition, it is further appreciated that certain features discussedwith respect to specific embodiments can, in many instances, be readilyadapted for use in one or more other contemplated embodiments that aredescribed herein. It would be readily appreciated by one of ordinaryskill, given the present disclosure that many of the features describedherein possess broader usefulness outside of the specific examples andimplementations with which they are described.

Rogowski Coil Principles—

In order to better understand various design considerations inimplementing the methodologies for the manufacture of exemplary coils asdescribed subsequently herein, it is useful to understand the underlyingprinciples that govern the behavior of a Rogowski-type coil. As is wellunderstood in the electronic arts, the voltage produced by a Rogowskicoil is driven by Equation (1) below:

$\begin{matrix}{V = {\frac{{- {AN}}\;\mu_{0}}{l}\frac{\mathbb{d}I}{\mathbb{d}t}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$Where:

A=the area of one of the small loops;

N=the number of turns;

l=is the length of the winding;

μ_(o)=a magnetic constant; and

dI/dt=is the rate of change of the current in the loop.

In order for a real-life implementation to operate closer to thetheoretical behavior set forth in Equation (1), various assumptions aremade including that the turns are evenly spaced, and that the radius ofthe device is comparatively large as compared with the radius of theturns themselves. Accordingly, these assumptions and how they affect thesensitivity of the Rogowski coil itself should be kept in mind in thesubsequent discussion of various coil devices as set forth below.Current Sensing Apparatus—

Referring now to FIGS. 1-1B, a first embodiment of a current sensingapparatus 100 is shown and described in detail. Specifically aRogowski-type current sensing apparatus is illustrated in the embodimentof FIGS. 1-1B. FIG. 1 illustrates the main elements associated with thecurrent sensing apparatus including a wound coil 102, a pass through orreturn conductor 104 and a segmented header 110.

As can be seen in FIG. 1, a first salient advantage of this device 100over other prior art Rogowski coils is readily apparent. Specifically,typical prior art Rogowski coils emphasized a uniform distribution ofcoil windings throughout the entire loop of the device, which waslargely believed to be necessary in order to achieve adequate electricalperformance for the device. However, it has been discovered by theAssignee hereof that such prior art construction is not only difficultto manufacture (resulting in relatively high selling prices for thedevice), but also not necessary in order to achieve a desired level ofelectrical performance for the device. Rather, by segmenting the currentsensing apparatus 100 into multiple substantially uniformly wound coilsegments 102, the underlying device is not only easier to manufacture,but provides similar or improved electrical performance over traditionalRogowski coil devices.

In an exemplary embodiment, the coil segments 102 are wound on a linearmandrel using a bonded wire winding. Moreover, a regular insulated wiremay also be used in conjunction with a bonding/gluing process. Bondedwire is a well-established product/process that is used to produceso-called “air coils”. Air coils themselves are inductors, and have beenconventionally used in RFID tags, voice coils, sensors, and the like.The materials and manufacturing equipment for producing bonded wire arecommercially available from a variety of sources known to the artisan ofordinary skill. Bonded wire is essentially an enamel-coated wire havingadditional coating applied (by either the wire vendor or the devicemanufacturer) to the outer surfaces of the enamel. Generally, duringwinding, the bonded wire coating may be activated (normally by heat,although other types of processes including radiation flux, chemicalagents, and so forth) to cause the coated wires to stick/bond together.This approach provides certain benefits and cost economies in thecontext of electronic component production. By using bonded wire, thecoil segment 102 itself becomes a self supporting structure. The use ofbonded wire generally is well known, and its use in constructinginductive devices is described in detail at, for example, co-owned U.S.patent application Ser. No. 10/885,868 filed Jul. 6, 2004 and entitled“Form-less Electronic Device and Methods of Manufacturing”, the contentsof which are incorporated herein by reference in its entirety.

The device 100 of FIG. 1 illustrates only a single coil segment 102installed in the segmented header 110, although it is appreciated thatthe device 100 is intended to operate with eight (8) coil segments asillustrated. Furthermore, while eight (8) coil segments are shown, it isappreciated that more or less segments can be added depending largely onthe overall size of the current sensing apparatus 100 and its desiredshape/profile. The ability to modify the number of coil segmentsprovides a distinct competitive advantage over prior art methods ofmanufacturing current sensing apparatus. Specifically, as the number ofcoil segments increases (i.e. advances towards a theoretic infiniteamount of segments), the behavior of the current sensing apparatus willtend to perform more like an ideal coil, however this is at the expenseof manufacturing complexity and cost. Conversely however, the number ofsegments can also be decreased until a minimum acceptable level ofelectrical performance has been achieved, thereby minimizingmanufacturing complexity as well as manufacturing cost.

Referring now to FIGS. 1A and 1B, the construction of the exemplaryembodiment of the segmented header 110 is more easily seen. Thesegmented header 110, in the illustrated embodiment, comprises eight (8)cavities 112, each associated with individual ones of the coil segments102. Preferably, the segmented header 110 is constructed from aninjection molded polymer material, although other construction materialsincluding without limitation composites, fibrous materials (e.g., paper)and combinations of the foregoing as well as alternative methodologies(e.g., transfer molding or assembly/adhesive processes) would be readilyapparent to one of ordinary skill given the present disclosure. Inexemplary embodiments, multiple ones of pass through conductor retainingfeatures 114 are positioned at multiple points along the segmentedheader, and between adjacent cavities 112 and are utilized to retain thepass through conductor (or conductors) 104 (FIG. 1) at a desiredlocation with respect to the positioned coil segments 102. The retainingfeatures 114, in the illustrated embodiment, position the pass throughconductor(s) 104 along the longitudinal axis of each of the coilsegments, although it is recognized that the positioning of the passthrough conductor(s) may be varied (and in the case where multipleconductors may be used, may actually occupy different positions withinthe segments). See, for example, the discussion of FIG. 7 subsequentlyherein. In addition, post features 116 provide a place for thewire-wrapping of interconnection wires between segments.

While, the current sensing apparatus illustrated in FIGS. 1-1B isspecifically adapted for applications in which the conductor from whichthe current will be ultimately sensed is capable of being passed throughthe center portion the apparatus 100, it is recognized that thesegmented header can be manufactured such that it is not a staticuniform structure. For example, it is recognized that the apparatus 100could be hinged such that segmented header 110 is capable of beingwrapped around the current carrying conductor for purposes ofinstallation, or to permit measurement/testing by an operator/installerin the field. Furthermore, a hinged segmented header could also bereadily adapted so that the flexible nature of the header operates inmore than just a single rotational degree of freedom. For example, thesegmented header could not only be adapted so as to permit the enclosedloop of the device to be opened and closed but also allowed to pivot andtwist so as to facilitate the ability for the segmented header to beaccommodated into any number of difficult installation locations in thefield.

The opposing end (i.e. the portion that is not hinged) could thenfurther be adapted with a retaining mechanism (such as a snap and thelike) that retains the hinged apparatus in its closed form. It isfurther recognized that this can be accomplished without hinges (e.g.via the use of dowels, snaps, the tension of the pass through conductor,etc.) or via the segmentation of the header 110 into two or moreseparable or movable portions depending on the needs of the system inwhich the apparatus will be ultimately installed. The separable ormovable segmented embodiment of the current sensing apparatus 100described in FIGS. 1-1B is also recognized to be equally applicable tothe other current sensing apparatus embodiments described subsequentlyherein.

It should also be noted that the header 110 is, in certain applications,readily modified to facilitate the mounting of the current sensingapparatus onto an external substrate (whether via surface mount orthrough-hole applications). For example, in through hole applications,the header 110 incorporates apertures (not shown) which hold andposition the ends of the conductors used in the current sensingapparatus at a predetermined spacing. These conductors are preferablyformed from a conductive wire of sufficient thickness that deformationof the wire prior to installation is unlikely. In surface mountapplications, the header is readily adapted with two or more conductiveareas. These conductive areas can either be formed from discretemetallic plates that are attached to the header or alternatively,incorporated via any number of well known polymer plating processes. Theends of the conductors can then be electrically coupled to theconductive areas via soldering, resistive welding, etc., so as to forman electrical connection between the current sensing apparatus windingsand the conductive areas to be mounted on an external substrate via asurface mounting process.

The current sensing apparatus (whether static or otherwise) can alsooptionally be encased in a clamshell cover or otherwiseencapsulated/molded/over-molded, etc. to protect against dirt and debrisas well as provide enhanced resistance to high voltages from, forexample, the conductor that is being measured by the current sensingapparatus. In addition, it has been found that in certainimplementations, the performance of the current sensing apparatus isextremely sensitive to deformations to the coil segments 102.Accordingly, by encasing the current sensing apparatus in a clamshellcover or otherwise encapsulating the windings, the performance of thecurrent sensing apparatus can be protected at a relatively inexpensivecost to the end customer. In addition to static embodiments (i.e. wherethe encased apparatus 100 is substantially rigid), it is recognized thatflexible embodiments can be readily implemented by using an encasementthat is flexible. Such a flexible device is, in an exemplary variant,formed by utilizing a rubberized shrink tubing disposed about at leastportions of the header 110.

Referring now to FIG. 1C, an alternative embodiment of the currentsensing apparatus illustrated in FIGS. 1-1B is shown and described indetail. Specifically, the embodiment of FIG. 1C illustrates acontinuously constructed helical coil for use with or without a headeror bobbin element as illustrated in FIG. 1. The current sensingapparatus 180 of FIG. 1C is effectively divided into segments 102 viause of a bead of adhesive 120 disposed e.g., on the inner circumferenceof the coil. Depending on the particular application, the types ofadhesive utilized can very widely. For example, where some flexibilityis desired within individual segments 102, a flexible adhesive (such assilicone) is used to allow some movement between individual turns ofwire within a segment 102. Alternatively, where flexibility is notdesired, a harder adhesive, such as a two-part epoxy, is used to limitthe amount of movement between individual turns of wire within asegment.

In the embodiment illustrated, the current sensing apparatus is formedon a mandrel in one continuous winding. The adhesive is then placed insegmented portions 102 on the inner diameter of the finished currentsensing apparatus using an auto-dispensing apparatus, therebysubstantially automating the manufacture of the current sensingapparatus. Note also that the return conductor (not shown) is routed inthe interior of the coil prior to winding. Although the adhesive isprimarily envisioned as being placed on the inner diameter of thefinished current sensing apparatus, it is recognized that alternativeembodiments could readily place the adhesive anywhere else on thewindings (such as the outer diameter) and even at multiple locations onthe windings (to further secure and minimize movement between adjacentwindings in any given segment). In addition, while the adhesive isprimarily envisioned as being disposed onto the windings in discretesegments, it is recognized that the bead of adhesive placed on thewindings can be continuously applied along the length of the windings,especially in cases where the adhesive used cures in a flexible form.

Advantageously, the foregoing process also lends itself to mass,parallel manufacturing operations. For instance, one long mandrel can beused, with the segments for many coils being formed (and cured ifapplicable) thereon, with the foregoing adhesive being applied rapidlyin one movement down the mandrel. The individual coils can then besevered on the mandrel (or after removal of the entire assembly from themandrel if desired), and the individual severed coils formed into thedesired shape (e.g., substantially circular or polygonal) andterminated. Similarly, multiple such mandrels can be processed inparallel, up to the limitations of the manufacturing equipment. Suchmass manufacturing provides yet additional economies of scale over thoseafforded by the coil design alone.

The device of FIG. 1C can also be encapsulated within a host compound ifdesired (e.g., potting compound, silicone, etc.) such that itsmechanical rigidity is substantially maintained, at least in thecritical dimensions. Specifically, it has been recognized by theinventor(s) hereof that the coils described herein may in many cases besensitive (in terms of degradation in performance) to changes in thecross-sectional area or profile of the turns of each segment. Forinstance, if the coils of the segments in the device of FIG. 1C werecrushed or distorted, the accuracy of the device as a whole can degradesignificantly. This dimension is more important than, for example,maintaining the “circularity” of the device as a whole, as well asmaintaining the conductor(s) being monitored within the geometric centerof the coil/polygon, the device advantageously being largely tolerant tothe latter. Accordingly, the mechanical stability of at least thecross-sectional area of the coil turns is a salient consideration inmany applications. Whether such stability is maintained via use of ahard or rigid exterior “shell” (e.g., a case, or alternatively a sleeveor other such arrangement which enshrouds the exterior of the coil), orvia encapsulation, or via internal support such as a bobbin or header islargely a design choice.

FIG. 1D illustrates a top down view of a current sensing apparatus 100as illustrated in, for example, FIG. 1C that does not possess a headerelement as illustrated in FIGS. 1-1B. Specifically, FIG. 1D illustratesa first exemplary way of making the current sensing apparatusfield-installable around a conductor (without necessitating the removalof the conductor from the device to which the conductor is attached).The current sensing apparatus illustrated in FIG. 1D possesses anoverlapping end 185 that can be routed around a conductor. Theoverlapping end can then be attached via an adhesive and the like to theother “end” of the coil. In this fashion, the free ends of the coildevice can be routed around the extant conductor installation, and thetwo ends overlapped and secured in place, thereby forming an effectivelyunbroken loop. While it will be appreciated that such an “overlapping”configuration has less precision than a comparable “unbroken” device(e.g., one with no ends per se, but rather made as a continuous loop),it also affords the aforementioned capability of field installationwithout disassembly, and also very low manufacturing cost (as describedin greater detail below).

It is noted that while the device of FIG. 1D illustrates the two ends ofthe coil overlapping in the vertical plane (i.e., normal to the plane ofthe Figure), the overlapping ends may overlap radially, whilemaintaining a “flat” vertical profile (i.e., one end being disposed at aradius smaller than that of the other end).

The two free ends of the device of FIG. 1C can be joined using anynumber of different techniques, including (without limitation): (1)merely utilizing the existing rigidity or malleability of the coildevice if applicable to maintain the two ends in the desired proximaterelationship (i.e., “bending” the device into shape); (2) an adhesive tobond the two ends; (3) a section of shrink tubing (e.g., shrinks whenheated) of the type well known in the electrical and environmentalsealing arts; (4) a plastic or other tie-wrap; (5) using tape (e.g.,electrical or duct tape); or (6) a molded or formed snap-fit assemblydisposed on the two respective ends. Each of the foregoing (to varyingdegrees) provides the benefit of very low cost, especially when used inconjunction with the cost-effective forming techniques for the deviceitself.

FIG. 1E illustrates an alternative field-installable embodiment of thedevice, in which the free ends of the current sensing apparatus 100 abutone another at 190. The embodiment of FIG. 1E is anticipated to behigher in cost to manufacture than that shown in FIG. 1D, but providesbetter electrical/magnetic performance (precision) over the previousembodiment illustrated in FIG. 1C, due largely to the fact that theabutted ends effectively allow the coil to be nearly “perfect” in shape,and obviate any overlap (which causes magnetic distortions and leakage).The ends of the current sensing apparatus can be abutted using anynumber of assembly techniques including, without limitation: (1) alocating pin coupling; (2) a magnetic coupling; (3) a screw-on coupling;(4) a shrink tube coupling; and (5) a snap/pivot type coupling. Withregards to the use of a magnetic coupling, it should be noted that theuse of magnet does not influence a change in the current to be measured(i.e. dI/dt) and accordingly, advantageously does not affect theelectrical performance capabilities of the device. The embodiment ofFIG. 1D is somewhat more costly to manufacture than that of FIG. 1C (duein large part to the cost of the abutting requirement for the coupling),yet also provides greater precision.

It will also be recognized that the embodiments of FIGS. 1D and 1E maybe fashioned so as to be flexible in multiple dimensions. For instance,in one variant, the coil ends can be pulled apart somewhat (so as topermit wrapping around an installed conductor or bus bar) due to theflexibility of the coil (particularly, the gaps between segments), yetalso varied vertically with respect to one another (i.e., maintain thesame radius, yet move relative to one another as torsional forces areapplied to both ends). In another variant, only a prescribed portion ofthe coil (e.g., a “hinge” region; not shown) is permitted to flexsignificantly. This can be accomplished in any number of different ways,such as by using a thinner covering material, or actual mechanicalhinge, in the hinge region, so that it flexes preferentially in thatregion.

Referring now to FIGS. 2-2C, a second exemplary embodiment of a header-or bobbin-based current sensing apparatus 200 is shown and described indetail. Specifically, the current sensing apparatus 200 of FIGS. 2-2Ccomprise multiple ones of segmented bobbin elements 210. Each of thesebobbin elements 210 is disposed next to one another via an optionallyhinged coupling 220. In one exemplary embodiment, this hinged coupling220 includes features (such as snaps and the like) which retain adjacentsegmented bobbin elements so that they remain attached to one another,however it is recognized that in alternative embodiments the hingedcoupling may provide only a pivoting, as opposed to a pivoting andretaining function. In an alternative embodiment, the hinged couplingmay be accomplished by molding a thin web of connecting material betweenadjacent ones of bobbin elements 210. Such a configuration could be madestatic (such as for use in embodiments in which the final applicationgeometry is known) or flexible as described previously herein. Thecoupling may also be made frangible; i.e., severable after a limitednumber of loading cycles, if desired, so as to facilitate selectiveseparation of the components.

Referring now to FIGS. 2 and 2A, a partial segment of a current sensingapparatus 200 is shown. Specifically, only a forty-five degree (45°)segment of a three-hundred sixty degree (360°) apparatus 200 isillustrated. Accordingly, as can be seen in the illustrated embodiment,the complete apparatus 200 would consist of eight (8) segmented bobbinelements 210. While eight elements are contemplated, this number isarbitrarily defined by the underlying geometry of the current sensingapparatus application as well as defined performance parameters. Hence,it is readily recognized that more or less elements or elements ofdifferent shapes or configurations (including also heterogeneous “mixes”of two or more different bobbin element configurations) could beutilized in alternative embodiments.

The embodiment illustrated in FIGS. 2-2C also includes a centralpassageway 230 that is intended to position the pass through conductorat a precise location within each of the segmented bobbin elements. Inthe illustrated configuration, the passageway is positioned along thelongitudinal axis (i.e., the geometrical center) of each of thecylindrical bobbin elements 210; however, as noted elsewhere herein, theposition of the central conductor(s) may be (i) non-symmetrical withrespect to the cross-section of passageway 230 or bobbin element; (ii)may be variable or changeable; and/or (iii) may reside at otherlocations.

FIGS. 2B and 2C illustrate differing perspective views of a singlesegmented bobbin element 210 according to one embodiment. The bobbinelement 210 is characterized by a winding channel 212 adapted forreceiving one or more layers of windings, while flanges 218 retain thewindings in the winding channel 212 resulting in a uniform distributionof the windings within the bobbin element 210. While the winding channelis illustrated with a smooth winding barrel, it is appreciated thatgrooves could be formed into the winding barrel in order to provideadditional features to guide the windings so that they are wound moreuniformly. Moreover, the cross-section of this “barrel” need not besymmetric, and/or can also include segmentation (i.e., may comprise anoctagon, ellipse, polygon, etc. in cross-section).

Positioned on opposing ends of the flanges are alignment posts 216positioned above standoffs 240. These alignment posts 216 are optionalbut are utilized to facilitate individual placement of the bobbinelements 210 within an encapsulating header (see for example FIG. 4A,460 described subsequently herein). Routing posts 214 are utilized forfacilitating the routing of the windings between individual ones ofbobbin elements 210 during automated winding on a mandrel as will bediscussed more fully subsequently herein. These routing posts 214 act asentry/exit points for the wire wound within the winding channel 212.

Recall the discussion of the hinged coupling 220 with regards to FIG.2A. As can be seen in FIGS. 2B and 2C, the hinged coupling comprises aprotruding portion 222 and a respective receptacle portion 224 which issized so as to accommodate the protruding portion from an adjacentbobbin element 210. Routing channel 232 can also optionally be utilizedto route the exit wire of the last segment to the return wire inside thecoil. Note that in the illustrated embodiment the hinged coupling 220does not include elements that allow adjacent elements 210 to remainmovably coupled to one another. Rather, the tension associated with therespective windings and pass through conductor is actually used toretain the assembled current sensing device in its finished torus-likeshape. However, it is recognized that alternative embodiments mayreadily include features that physically couple adjacent elements 210 toone another, use adhesives or other bonding agents, etc.

Referring now to FIGS. 3-3D, yet another embodiment for a Rogowski-typecurrent sensing device 350 is illustrated. FIG. 3 illustrates a singlebobbin element 300, of which eight (8) are required (for the illustratedembodiment) to create a single current sensing device 350. It isrecognized that more or less bobbin elements, those of heterogeneousconfiguration, etc. could be utilized in alternative embodiments asdiscussed previously with respect to other embodiments. Unlike thebobbin element 210 of FIGS. 2-2C, the bobbin element 300 of FIG. 3 doesnot necessitate a hinged coupling. Instead, the bobbin element 300 ofFIG. 3 is constructed so that they collectively form the torus-likestructure of the current sensing device 350 when bobbin elements 300 areplaced adjacent to one another. See for example, FIG. 3B which showsexactly one half (i.e. four (4) bobbin elements) of the current sensingdevice 350. Each bobbin element includes a winding channel 310, which isdefined by respective flange elements 330. These flange elementsmaintain and define the winding width for the winding channel 310. Thebobbin element 300 further comprises routing posts 312 which again areutilized as exit/entry points for the winding as they exit and enter thewinding channel 310. In addition, these exit/entry points can also beused to anchor the pass through or return conductor prior to winding.Optional pass through conductor routing channels 314 are includedadjacent to the routing posts 312. The routing channels 314 are adaptedto accommodate one or more pass through conductors underneath thewindings placed within winding channel 310. Accordingly, the passthrough conductor which is routed through channel 315 advantageouslyhelps to maintain the structural integrity of the assembled device 350when assembled, via tension applied to the pass through conductor (notshown).

In an alternative embodiment, the pass through conductor can instead berouted through the center cavity 320 (i.e., along the inner diameter ofthe center cavity). Furthermore, the bobbin element 300 could be readilybe adapted to accommodate through a central passageway constructedwithin the center cavity 320 (similar to that shown in FIG. 2B, 230).These and other embodiments would be readily apparent to one of ordinaryskill in the art given the present disclosure.

FIG. 3A illustrates a side elevation view of the bobbin element 300shown in FIG. 3. Specifically, as can be seen in FIG. 3A, despite thecurved geometry of the bobbin element 300, center cavity 320 passes, inthe illustrated embodiment, in a straight line through the body of thebobbin element. This facilitates the automated winding of the bobbinelement (see e.g., FIGS. 3C-3D). Keyed notch 322 also passes linearlyalong the inside wall of the center cavity 320, thereby providing afeature that can be received within a respective slot (see FIG. 3D, 362)on a mandrel which allows the bobbin element 300 to be rotated withprecision during the winding process.

FIGS. 3C and 3D illustrate four (4) such bobbin elements 300 mounted ona mandrel 360. Note that because the bobbin elements 300 are configuredin a linear fashion, the automated winding of the final “torus-like”shape is very much simplified over a truly torus (circular) shape. Thecollar 370 is mounted on the end of the mandrel 360 and secures thebobbin elements onto the mandrel 360. The embodiment illustrated inFIGS. 3-3D can then optionally be encased in a header or housing, suchas e.g., an over-lapping clamshell type header (not shown) or otherencasement.

Referring now to FIGS. 4-4B, a fourth exemplary embodiment of a currentsensing apparatus 400 is shown and described in detail. Specifically,the current sensing apparatus 400 of FIGS. 4-4B comprise multiple onesof segmented bobbin elements 410. Each of these bobbin elements 410 aredisposed next to one another via the use of an external ring-like header460 (FIG. 4A). FIG. 4 illustrates a partial segment of the currentsensing apparatus 400 of FIG. 4A. Specifically, only a forty-five degree(45°) segment of a three-hundred sixty degree (360°) apparatus 400 isshown. Accordingly, in the illustrated embodiment, the completeapparatus 400 would consist of eight (8) segmented bobbin elements 410,as can be seen by counting the number of cavities 464 on the ring-likeheaders 460 of FIG. 4A. The bobbin element 410 illustrated in FIG. 4includes a central passageway 430 that is intended to position the passthrough conductor at a precise location within each of the segmentedbobbin elements. In the embodiment illustrated, the passageway ispositioned along the longitudinal axis of the cylindrical bobbin element410. The bobbin element 410 of FIG. 4 also includes an alternativepassageway 432 which can be utilized to route the return wire throughthe center of the bobbin segment for the purpose of facilitatingassembly. The bobbin element 410 is characterized by a winding channel412 adapted for receiving one or more layers of windings, while flanges418 retain the windings in the winding channel 412 resulting in auniform distribution of the windings within the bobbin element 410.Positioned on opposing ends of the flanges are alignment posts 416positioned above standoffs 440. These alignment posts 416 are optionalbut are utilized to facilitate individual placement of the bobbinelements 410 within the header 460. Routing features 422 are utilizedfor facilitating the routing of the windings between individual ones ofbobbin elements 410 during automated winding on a mandrel as will bediscussed more fully subsequently herein with respect to FIG. 4B. Theserouting features 422 act as entry/exit points for the wire wound withinthe winding channel 412.

FIG. 4B illustrates the individual bobbin elements 410 mounted on amandrel 470 for the purpose of the automated winding of individual onesof the bobbin elements. As can be seen, a slot 472 is machined orotherwise formed in the winding mandrel 470. This slot 472 is sized toaccommodate a respective feature 434 (FIG. 4) on the individual bobbinelements which facilitates the winding operation. A collar 480 is placedover an end of the mandrel 470 in order to secure and position theindividual bobbin elements 410 at a reliable location along the shaft ofthe mandrel. This approach permits repeatability and consistency duringthe winding process, without necessitating the use of vision equipmentto help locate the feed end of the automated winder.

Note also that all eight (8) segments 410 utilized to form the currentsensing apparatus are disposed on a single winding mandrel 470. Whileprevious embodiments (FIG. 3C) have illustrated only a portion of theentire sensing apparatus being formed at any one time on a mandrel, theembodiment of FIG. 4B illustrates an embodiment in which all segmentscan be wound in a single winding operation. The wound segments can thenbe subsequently removed from the mandrel and placed into the headers 460as shown in FIG. 4A.

Referring now to FIGS. 5-5C, yet another embodiment of a bobbin element510 for use in a current sensing device is shown and described indetail. The bobbin element illustrated in FIG. 5 is similar inconstruction with the hinged embodiment previously illustrated in FIGS.2-2C. Specifically, the embodiment illustrated in FIG. 5 is similar inthat it possesses a winding channel 512 defined by outer winding flanges518. Furthermore, the embodiment illustrated further includes routingposts 514 for facilitating the routing of magnet wire between adjacentones of winding channels (see FIG. 5C). The hinge element 522 also isadapted for receipt in a respective feature located on an adjacentbobbin element 510 and acts as a pivot point for the bobbin elements,similar to the functionality as described with regards to FIGS. 2-2C.See also the hinge point 550 illustrated in FIG. 5B. In addition, thecollective bobbin elements can then optionally be placed inside of aclamshell type cover (not shown) or other encasement, or between a pairof header elements (similar to that shown in FIG. 4A, 460).

However, unlike the previous embodiments discussed, the embodiment ofthe bobbin element 510 illustrated in FIG. 5 differs in that the passthrough or return conductor(s) (not shown) is not routed through thecenter aperture 534, as has been illustrated in the previous embodimentof FIGS. 2-2C; rather wire routing aperture 530 is utilized for thispurpose. The wire routing aperture 530 is positioned within the body ofthe winding barrel, the outer diameter of which defines the windingchannel 512. Such a configuration has advantages in terms of assembly,as the pass through conductor is resident on the inner diameter of thefinished current sensing device. Because the pass through conductor ison the inner diameter, the length of the pass through conductoradvantageously does not need to be significantly lengthened as theindividual bobbin elements 510 are formed into their final torus shape.This allows for, inter alia, greater simplicity and efficiency inmanufacturing and assembly.

In addition, as the pass through conductor is not positioned within thecenter aperture 534, it can be easily accommodated during the mandrelwinding process with the individual bobbin elements 510 each mounted onthe mandrel 560. Note also that flat surface 536 (as perhaps is bestshown in FIG. 5A) corresponds with a flat surface 570 located on themandrel 560. This geometry helps ensure that the bobbin elements 510spin as the mandrel spins.

FIGS. 6-6B illustrate yet another variant of the current sensingapparatus of FIGS. 5-5C. The embodiment of FIGS. 6-6B is similar in thatit is made up of bobbin elements 610 for use in a current sensingdevice. The bobbin element 610 comprises a hinged assembly similar tothat illustrated in FIGS. 2-2C. The bobbin element further possesses awinding channel 612 defined by outer winding flanges 618 and furtherincludes routing posts 614 for facilitating the routing of magnet wirebetween adjacent ones of winding channels (see FIG. 6B). The hingeelement 622 also is adapted for receipt in a respective feature locatedon an adjacent bobbin element 610 and acts as a pivot point for thebobbin elements, similar to the functionality as described with regardsto FIGS. 2-2C and FIGS. 5-5C. See also the hinge point 650 illustratedin FIG. 6B. The collective bobbin elements 610 can then optionally beplaced inside of a clamshell type cover (not shown) or other encasement,or between a pair of header elements (similar to that shown in FIG. 4A,460).

The embodiment of the bobbin element 610 illustrated in FIG. 6 differsover prior illustrated embodiments in one salient aspect; i.e., that thereturn conductor (not shown) is not routed through the center aperture634 or a wire routing aperture (FIG. 5A, 530) passing through thewinding barrel, as has been illustrated in previous embodiments. Rather,the wire routing slot 630 is utilized for this purpose. The wire routingslot 630 is positioned on the exterior periphery or outer diameter ofthe winding channel. Such a configuration has advantages in terms ofassembly as the return conductor is resident not only on the innerdiameter of the finished current sensing device, but also does not needto be threaded through an aperture, thereby simplifying assembly.

It is also noted that routing slot may be used to run the return wire(conductor) and/or a flexible cord inlay (non-conductor). For example,in one variant (see FIG. 6C), the wire being wound around the bobbinswould capture and secure the aforementioned cord (not shown) in theouter slot 631 to the individual bobbin elements, so as to provide aflexible hinge between them, and add mechanical stability (as well asprotect the crossover wire during assembly). This cord does not have tobe round in cross-section; in fact, it may have literally any crosssectional shape including without limitation square, rectangular,polygonal, oval/elliptical, or even be a composite of multiple discretestrands (e.g., braided).

Furthermore, because the return conductor is on the inner diameter, thelength of the return conductor does not need to be significantlylengthened as the individual bobbin elements 610 are formed into theirtorus shape, as previously discussed. In addition, as the returnconductor is not positioned within the center aperture 634, it can beeasily accommodated during the mandrel winding process with theindividual bobbin elements 610 each mounted on the mandrel 560illustrated in FIG. 5C.

Referring now to FIG. 7, various exemplary positions for a return orreturn conductor on a bobbin element 700 are shown. Specifically, FIG. 7illustrates various options for positioning the return conductor withrespect to the bobbin element 700 and the respective windings 710disposed on that element. While simultaneously illustrating multiplereturn conductors (720, 730, 740, 750, 760), it is recognized that inmost embodiments, only a single position for the return conductor willexist at a time. The various illustrated options are as follows (theseare not intended to be limiting, and other options exist):

-   Option (1) The return conductor 720 can be placed at the inner    diameter radius of the bobbin element 700, similar to the    positioning as set forth in the embodiment of FIGS. 5-5C;-   Option (2) The return conductor 730 can also be placed external to    the windings 710. While unconventional, it has been found that such    an arrangement is effective so long as the return conductor 730 is    in physical contact with the windings 710. It is appreciated that    the return conductor 730 can literally be placed anywhere along the    outer periphery of the windings 710;-   Option (3) The pass through conductor 740 can be placed at the    geometric center of the bobbin element 700 (i.e. along the    longitudinal winding axis) as set forth in, for example, FIGS. 2-2C;-   Option (4) The pass through conductor 750 can be positioned along    the outer diameter radius of the bobbin element 700 internal to the    windings 710; and/or-   Option (5) The pass through conductor 760 can be positioned    off-plane with respect to the inner conductor 720 and outer    conductor 750 positions as set forth in (1) and (4) above.    The various options discussed above with respect to FIG. 7 have    various electrical performance versus manufacturability tradeoffs.    For example, in some applications, the degradation in electrical    performance seen by a current sensing apparatus is not significant    enough to offset the benefits in terms of ease of manufacture by    placing the feed through conductor closer to the inner diameter of    the completed current sensing apparatus (as discussed above with    respect to, for example, FIGS. 5-5C). Alternatively, in high    performance and/or precision applications, the additional    manufacturing cost may be justified for the higher level of    performance/precision. Such tradeoffs would be readily understood by    one of ordinary skill given the present disclosure and accordingly    are not discussed further herein.

Referring now to FIG. 8, yet another embodiment of a current sensingapparatus 810 is shown and described in detail. Specifically, theembodiment of FIG. 8 addresses the special case where the currentcarrying conductor 820 to be sensed is oblong or otherwise irregular inshape. Such an oblong shape as illustrated is common in, e.g., manyelectrical utility company applications (such as for example inso-called busbars utilized in electrical power distributionswitchboards, distribution stations and substations). As discussedpreviously, the current sensing apparatus of previous embodiments wasprimarily contemplated as being generally torus-like in shape as isconventional in the prior art. However, it has been found that byelongating the current sensing apparatus 810 such that it now comprisesa generally oval or elliptical type shape to accommodate the oblongshape of the conductor 820, improved electrical performance is achieved.Recall from above that the voltage sensitivity of a Rogowski coil isdriven by equation (1) in which:

$\begin{matrix}{V = {\frac{{- {AN}}\;\mu_{0}}{l}\frac{\mathbb{d}I}{\mathbb{d}t}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$Accordingly, by possessing a generally oval type shape, the currentsensing apparatus has a relatively shorter length (than a prior artround Rogowski coil), thereby increasing the voltage level seen in thecurrent carrying conductor 820. In addition to curved configurations, itis also recognized that square and rectangular configurations can beutilized as well.

In embodiments that utilize the segmented bobbin elements (e.g.segmented bobbin element 210, FIG. 2) or alternatively the headerelement (110, FIG. 1), it is appreciated that the center opening 830 canbe sized to accommodate the conductor 820 without having to physicallyvary the shape of the segmented windings themselves. In other words, thebobbin element or header element itself is physically sized toaccommodate the conductor. FIG. 8A illustrates on such exemplaryimplementation. Specifically, FIG. 8A illustrates a current sensingapparatus 850 formed of a multiplicity of segmented bobbin elements 852each having a number of conductive windings 854 wound thereon. Thesesegmented bobbin elements are then utilized in conjunction withalignment elements 856 so as to align the bobbin elements around theconductor 820 to be measured. In this manner, the alignment elementsprevent skewing and biasing of the current sensing apparatus 850 whenplaced around the conductor, and further provide accurate and repeatableplacement (ensuring consistent electrical performance for currentsensing apparatus installed in the field).

Moreover, in other embodiments, the alignment elements areinterchangeable, such as to accommodate bus bars of different shapes andsizes, and/or the placement of the conductor within different portionsof the center opening of the coil.

Similarly, for the free-space or former-less embodiments describedelsewhere herein, a central alignment element can be used whichpositively places (and orients) the sensing apparatus around theconductor.

FIGS. 8B and 8B-1 illustrates yet another embodiment of the sensing coilof the invention, rendered in a substantially rectangular form factorhaving four (4) (or multiples of 2) segments corresponding to each ofthe four sides of a rectangular conductor. As shown in FIG. 8B, the foursegments 870, 872, 874, 876 are disposed at 90 degrees relative to oneanother, corresponding to the four sides of the bus bar 878. The lateralcoil segments 872, 876 are longer in length (and have more turns) thanthe end coil segments 870, 874, although it will be appreciated thatother configurations may be used (including four identical segments,segments of the same length but different turn density, segments ofdifferent length but the same turn density, and so forth). Moreover, theconfiguration of FIG. 8B can be used with square conductors (not shown),or multiple conductors whose composite outline forms an effectiverectangle or square.

The device 868 of FIGS. 8B and 8B-1 is in the illustrated embodiment,disposed within a hard shell or case 880 (shown with part of the case“clamshell” removed in FIG. 8B), although other approaches (includingfor example encapsulation, or use of a header or bobbin for support) maybe used as well.

FIG. 9 illustrates an alternative to the substantially round windingchannels 910 associated with typical prior art current sensingapparatus. As can be seen in FIG. 9, the cross sectional length of thecurrent sensing apparatus 920 has been lengthened along the path of theconductor 940 in which current is desired to be sensed. The feed throughconductor 930 can be placed within the current sensing apparatus 920 inany number of locations, considering the various design tradeoffs, asset forth in the discussion of FIG. 7 above. Accordingly, because thecross sectional area (A) has been increased (as set forth in Equation(1) above), the voltage level measuring the current carrying conductor940 increases. While prior art Rogowski-type coils have typicallymaintained their traditionally circular and torus-like shapes due to afear that deviating from these shapes would adversely impact theelectrical performance of the coil, it has been found that in manytypical applications, such deviations are acceptable in implementation.

In yet another embodiment of the invention, two or more “layers” ofwindings may be utilized to form the coil and the return conductor. Forexample, in one variant, a first layer of windings is applied over thetop of the bobbin or header segments so as to effectively providecomplete coverage of the segmented bobbin or header elements. Atcompletion of the first layer, the same winding is “doubled back” uponitself and over the top of the first layer so as to form a second layer.The first layer in effect acts as a return conductor within the secondlayer, although the return conductor layer need not necessarily be thefirst layer. It will be appreciated that more layers for the returnand/or “top” (second) layer may be used as well if desired. Moreover,the winding densities and topologies may be varied for each layer, suchas e.g., where the return conductor layer is wound at a lower density(greater inter-turn spacing) than the top layer.

It is also appreciated that the aforementioned “layered” approach neednot be used in conjunction with a bobbin or header at all. For instance,in one “free standing” variant, bonded wire of the type discussedpreviously herein is used to form the first and subsequent layers (e.g.,wound atop a mandrel or other removable structure, and then bonded, andthe mandrel/structure removed). Alternatively, non-bonded wire can beused, and subsequently encapsulated or held in place with an adhesivebefore removal of the mandrel/support. Myriad other variations will beappreciated by those of ordinary skill given the present disclosure.

Referring now to FIGS. 16-16D, yet another exemplary embodiment of aheader- or bobbin-based current sensing apparatus 1600 is shown anddescribed in detail. Similar to other disclosed embodiments, the currentsensing apparatus 1600 of FIGS. 16-16D comprise multiple ones ofsegmented bobbin elements 1610. FIG. 16 illustrates a single one ofthese segmented bobbin elements 1610 in detail, with the illustratedbobbin element 1610 adapted for coupling to another segmented bobbinelement via a hinged coupling 1620. Other coupling types may be usedconsistent with this embodiment as well.

In the illustrated embodiment, this hinged coupling 1620 includes a pairof hinge features 1621, 1623, with a through-hole 1632 disposed on eachof these features that is sized to accommodate an inserted pin (item1650, FIG. 16A). The hinged coupling in combination with the insertedpin is somewhat akin to what is seen on a typical door hinge. Thesehinged couplings include an outer hinged coupling pair 1623, and aninner hinged coupling pair 1621, which are designed so as to retainadjacent segmented bobbin elements. Specifically, the outer hingedcoupling pair 1623 is spaced apart at a distance in which a respectiveinner hinged coupling pair 1621 can fit therebetween. It will berecognized that each segment element 1610 (i.e., each side or interfaceportion thereof) can include (i) the outer hinge pair, (ii) the innerhinge pair, or (iii) some mixture of the foregoing. In one variant, thesegment elements are each made identical to one another for ease ofassembly and lower cost, although this is by no means a requirement.Moreover, the segment elements can have at least 2-dimensional symmetrysuch that they can be inserted into the assembly in two differentorientations, thereby simplifying assembly from the standpoint that anautomated or manual assembly process does not have to orient the partcorrectly in all three dimensions for assembly (rather only with respectto two dimensions).

Each of the hinged coupling pairs illustrated in FIG. 16 alsoincorporate a chamfered inlet for the through hole 1632. This chamferedinlet facilitates the insertion of the inserted pin order to easeassembly.

Furthermore, and similar to other illustrated bobbin embodimentsdiscussed previously herein, bobbin element 1610 of FIG. 16 alsoincludes a winding channel 1612 with flanges 1618 disposed on eitherside of the winding channel. The winding channel is further defined by aspool or barrel 1613 which provides the radial mechanical support forthe insulated windings.

The bobbin element also includes a return conductor passageway 1630positioned within a return conductor alignment feature 1634. The returnconductor passageway 1630 is intended to position the pass-throughconductor at a precise location within each of the segmented bobbinelements. In the illustrated configuration, the passageway is positionedalong the longitudinal axis (i.e., the geometrical center) of each ofthe cylindrical bobbin elements 1610; however, as noted elsewhereherein, the position of the central conductor(s) may be (i)non-symmetrical with respect to the cross-section of passageway 1630 orbobbin element; (ii) may be variable or changeable; and/or (iii) mayreside at other locations.

FIG. 16 also illustrates some additional features not present in some ofthe other illustrated bobbin element embodiments, although it isrecognized that these other illustrated embodiments could readilyincorporate these features. These features include winding alignmentbosses 1638 along with associated alignment holes 1636. These bosses andholes are useful during the winding process to ensure proper alignmentis maintained between adjacent bobbin elements 1610 (i.e., to preventrelative twisting when wire is being wound on a winding mandrel, etc.),and to maintain stability when the bobbin elements are rotated at highspeed.

Conductive clip apertures 1616 are also included on the illustratedembodiment of the flange. These apertures 1616 are sized to accommodatea respective clip (not shown), which is then used to facilitate theconnection of the windings resident with the winding channel 1612 to thereturn conductor and to an external connection (see e.g. themanufacturing discussion with relation to, inter alia, FIGS. 18A-18S).Note that the illustrated embodiment of the bobbin element 1610 includestwo (2) substantially identical clip apertures 1616 located on opposingflanges 1618. However, alternative embodiments could utilize “keyed”clip apertures that differ so as to, for example, prevent the insertionof improper clips (i.e., where clips differ between the “start” and“finish” winding ends of the Rogowski coil device).

Furthermore, while illustrated as a so-called post insertedconfiguration, it is recognized that the conductive clip could also beinsert molded into the flange (i.e., during the injection molding of thebobbin element itself), thereby securing the clip to the bobbin element.Yet other techniques recognized by those of ordinary skill given thepresent disclosure may be used as well.

FIG. 16A illustrates the total or collective number of bobbin elements1610 in a single device 1600, coupled together via their respectivehinge coupling pins 1650. Note also that the windings 1660 have now beenadded to each of the bobbin elements as illustrated in FIG. 16A. Asdiscussed previously herein, the bobbin element 1610 is characterized bya winding channel adapted for receiving one or more layers of windings,while flanges retain the windings in the winding channel resulting in atleast a substantially uniform distribution of the windings within eachof the bobbin elements 1610. While the winding channel is illustratedwith a smooth winding barrel or spool, it is appreciated that groovescould be formed into the winding barrel in order to provide a means tofurther guide the windings during the winding process so that they arewound more uniformly. Moreover, while illustrated as a symmetric andcircular barrel, it is recognized that the cross-section of this“barrel” need not be symmetric, and/or can also include segmentation(i.e., may comprise an octagon, ellipse, polygon, etc. in cross-section)as discussed previously herein.

FIG. 16B illustrates an exploded view of the Rogowski coil device 1600as each of the bobbin elements are about to be mounted within a housing.The housing in this embodiment is comprised of a top 1670 and a bottom1680 housing cover, although other configurations may be used.

FIGS. 16C-16D illustrate how each of the bobbin elements 1610 aresupported within the housing. As can be seen in FIG. 16D, the bottomhousing cover 1680 includes a number of features that facilitate deviceassembly. More specifically, these features aid in the accurateplacement of the bobbin elements 1610 within the housing. Hinge pinreceptacle features 1684 are adapted to accommodate the hinge pins 1650present on the assembled grouping of bobbin elements 1610. Thesefeatures help ensure that each of the bobbin elements 1610 is preciselyspaced to ensure repeatable electrical performance from the underlyingRogowski coil device 1600, and also aid in the assembly process byregistering the various components of the core at a desired location.Flange support features 1682, 1686 are also sized to accommodate theshape of the bobbin elements and ensure that they are adequatelysupported within the bottom housing 1680. The bottom housing alsoincludes a central aperture 1688 that is designed to accommodate theelectrical conductor(s) to be measured by the Rogowski coil device 1600.As previously noted, this central aperture may be (i) of a shape that isnot circular and/or non-symmetric; and/or (ii) made replaceable toaccommodate different conductor cross-sections (e.g., round,side-by-side, rectangular “bar”, etc.).

Referring now to FIGS. 17-17C, yet another exemplary implementation of aheader-based or bobbin-based current sensing apparatus 1700 is shown anddescribed in detail. This embodiment incorporates a so-called “livinghinge” design, as described in greater detail below. FIG. 17 illustratesa singular segmented bobbin element 1710, which in combination withother bobbin elements (e.g., six (6) in the illustrated embodiment),forms the Rogowski coil device 1700 illustrated in FIG. 17A. Similar toprevious embodiments discuss herein, the bobbin segments illustrated inFIGS. 17-17C each are disposed next to one another in a common plane viaa hinged coupling 1720. In the illustrated embodiment however, thishinged coupling 1720 includes a flexible hinge feature 1725 thatconnects the flange 1718 of the bobbin element with a coupling portioncomprised of a winding spool portion 1721 along with an insertableportion 1723, the latter sized to fit within an associated aperture 1722located on the winding channel 1712 of an adjacent bobbin element. Thewinding spool portion 1721 includes a curved surface which is shaped topossess a diameter substantially identical to the underlying windingspool. In addition, the thickness of the winding spool portion of thehinged coupling is approximately the same as the depth of the spoolcavity 1727, such that when the hinged coupling is coupled to anadjacent bobbin element, the coupling provides a near seamless fit.

Similar to other illustrated bobbin embodiments discussed previouslyherein, the bobbin element 1710 of FIG. 17 includes a winding channel1712 defined by a barrel or spool 1713, and flanges 1718 disposed oneither side of the winding channel in order to define a winding “window”for the bobbin. Furthermore, the bobbin element includes a returnconductor passageway 1730 positioned within a return conductor alignmentfeature 1734. The return conductor passageway 1730 positions the passthrough conductor at a precise location within each of the segmentedbobbin elements as discussed previously. In the illustratedconfiguration, the passageway is positioned along the longitudinal axis(i.e., the geometrical center) of each of the cylindrical bobbinelements 1610; however, as noted elsewhere herein, the position of thecentral conductor(s) may be located at a variety of differing locationswhile still providing adequate electrical performance in most currentsensing applications.

FIG. 17 also illustrates the use of winding alignment bosses 1738 alongwith associated alignment holes 1736. These bosses and holes are usefulduring the winding process to ensure proper alignment and stability ismaintained between adjacent bobbin elements 1710 (i.e., to preventrelative twisting when wire is being wound onto a winding mandrel,etc.). In addition, conductive clip apertures 1716 are included on theflange. These apertures 1716 are sized to accommodate a respective clip(not shown) which is then used to facilitate the connection of thewindings resident with the winding channel 1772 to the return conductorand to an external connection (see e.g. the manufacturing discussionwith relation to, inter glia, FIGS. 18A-18S). Note that the illustratedembodiment of the bobbin element 1710 includes two (2) substantiallyidentical clip apertures 1716 located on opposing flanges 1718.Furthermore, while illustrated as a post-inserted clip design, insertmolding or other techniques could be readily substituted as well.

FIG. 17B illustrates a cross-sectional view of the Rogowski coil device1700 of FIG. 17A, taken along line 17B-17B. The cross-sectional view ofFIG. 17B helps illustrate the fit of the various elements of the hingedcoupling. Specifically, it shows the insertable portion 1723 of thehinged coupling pushed against the winding spool aperture 1722 so as toprevent over insertion when coupling the various bobbin elements. Also,as can be seen in FIG. 17B, the external surfaces 1731 of the returnconductor alignment feature 1734 is disposed offset from (i.e., inwardof) the external surface 1719 of the bobbin element 1710. This offsetallows for the insertion and alignment of, for example, the start andend clips (1890, 1892 in FIGS. 18A and 18B, respectively).

Referring now to FIGS. 19A-19C, another embodiment of individualizedbobbin elements 1900 are shown and described in detail. Each of thesebobbin elements includes a winding channel 1920 along with respectiveflanges 1910 disposed on either end of the winding channel. However,unlike many of the other embodiments disclosed herein, the illustratedbobbin element of FIG. 19A does not include any sort of a hingedcoupling. In other words, the bobbin elements 1900 are designed to bepositioned onto a substrate for example, without necessitating that theyphysically couple with an adjacent bobbin element. The obviation of ahinged coupling allows for the individualization of each of the bobbinelements, which inter alia, adds additional flexibility to how each ofthe bobbin elements is ultimately positioned with respect to otheradjacently disposed bobbin elements within a complete inductive devicesuch as the exemplary Rogowski coil-type devices discussed herein.

The bobbin element of FIG. 19A includes a number of self-leadedterminals 1912 positioned on the side wall 1924 of the flange 1910. Theself-leaded terminals are arranged such that when windings 1922 arewrapped around the terminals, these windings will protrude past an upper(or lower) surface 1914 after these windings are subsequently secured tothe terminal via, for example, a eutectic solder or the like. Exemplaryembodiments using self-leaded terminals in other applications arediscussed in co-owned U.S. Pat. No. 5,212,345 filed Jan. 24, 1992 andentitled “Self-leaded surface mounted coplanar header”, the contents ofwhich are incorporated herein by reference in its entirety. Theseself-leaded terminals enable the bobbin element to be mounted to, forexample, a printed circuit board via conventional processing techniquessuch as an infrared (IR) solder reflow process. The self-leadedterminals include their own respective flanges 1916 to retain thewindings 1922 and in the illustrated embodiment, also include agenerally triangular winding cross section although othercross-sectional shapes (e.g. round, oval, polygonal, etc.) could bereadily adapted to the bobbin element illustrated.

In addition, the flanges 1910 include a number of routing features 1918which help position and maintain the windings that are routed from thewinding channel to the self-leaded terminals.

While the embodiment illustrated in FIG. 19A includes self-leadedterminals that are formed simultaneously with the bobbin elementsthemselves using a high temperature polymer that can withstand thetemperatures experienced in conventional solder processes, it isappreciated that these self-leaded terminals could be readilysubstituted with metallic terminals that are either insert molded orpost inserted into the bobbin element. These metallic terminals couldeither be inserted into the sidewall 1924 of the flange or alternativelycould be inserted into the bottom (or top) surface 1914 of the bobbinelement which is useful, for example, when inserting through hole leadsinto the bobbin element.

Referring now to FIGS. 19B and 19C, an individualized bobbin elementassembly 1950 is shown and described in detail. Specifically, six (6)bobbin elements 1900 are shown mounted on a substrate in a generallycircular pattern about a hole 1960 located on the substrate, although itwill be recognized that other numbers and configurations of bobbinelements may be used consistent with the invention. This hole isintended to accommodate the conductor that is to be measured by theassembly 1950. FIG. 19C illustrates another feature of the illustratedembodiment with regards to the way the self-leaded terminals 1912 arearranged. Specifically, the self-leaded terminals are arranged in thisembodiment in a staggered fashion such that the inner terminals 1930(i.e., the terminals most closely positioned towards the center of thesubstrate) do not interfere with the inner terminals 1932 of an adjacentbobbin element. An advantage of such a staggered design feature is thatthe bobbin elements can be more closely positioned to one another,thereby improving upon the electrical performance of the assembly 1950as well as, or alternatively, reducing the overall footprint of theassembly. As is perhaps best seen in FIG. 19C, the self-leaded terminalsare staggered on both the lower terminals (that interface with substrate1970) as well as the upper terminals which, in the illustratedembodiment, do not interface with a substrate.

Referring now to FIG. 20A, one embodiment of a hinged self-leaded bobbinelement assembly 2050 is shown and described in detail. The self-leadedbobbin element assembly 2050 is similar in construction to theindividualized bobbin elements discussed previously herein with regardsto FIGS. 19A-19C, except that the bobbin elements 2000 in FIG. 20Ainclude a hinged coupling 2030. In addition, while the bobbin elementsin FIG. 19A are each individually wound and terminated, the embodimentillustrated in FIG. 20A is in the illustrated embodiment continuouslywound. For example, in one implementation, the windings start at theterminals 2012 at the first end 2002, and traverse across each of thewinding channels of each bobbin element 2000, finishing with thetermination of the winding at a terminal at the far end 2004. The hingedcoupling 2030 then allows for the bobbin elements to pivot with respectto one another.

FIG. 20B illustrates one such exemplary pivoting bobbin element at theend of the assembly 2050. As an alternative to a continuous winding,each of the bobbin elements can be wound individually such that thestart and end terminations for the windings reside on a single bobbinelement. The wound bobbin elements can then be assembled (e.g. via asnap fit) such that they are coupled via their respective hingecouplings 2030.

Referring now to FIG. 21, an exemplary substrate assembly 2100 utilizingthe bobbin elements of, for example FIG. 19A, which are sandwichedbetween a pair of substrates, is shown and described in detail.Specifically, the bobbin elements 1900 are shown sandwiched between anupper substrate 2110 and a lower substrate 2112. In the illustratedembodiment, the bobbin elements are electrically and mechanicallyconnected to the substrates via a surface mount connection. Thesubstrates (which may be heterogeneous or homogeneous in nature) are, inan exemplary embodiment, constructed from a fiberglass material overlaid with copper. The copper is subsequently etched so as to routecircuitry between the individual bobbin elements in order to complete adesired electrical circuit, such as the aforementioned current sensingRogowski principle circuit discussed elsewhere herein. The printedcircuit board substrates 2110, 2112 may either constitute single layersubstrates, or alternatively can be of a multi-layer type substrate. Inaddition to the routing circuitry, these substrates can, in someembodiments, also include mounting locations for discrete electroniccomponents or alternatively can incorporate electronic circuit elements(e.g. capacitive or inductive elements) within the body of the substrateitself. The substrates also include interface terminals that allow thecircuit assembly 2100 to physically and electrically interface with anexternal device. Such an illustrated embodiment is desirable where it isadvantageous to electrically couple each of the bobbin elements with oneanother using a mass termination processes such as IR reflow. Whilesurface mounted connections are primarily contemplated, it isappreciated that other techniques, such as through hole terminals, couldalso be used not only for the bobbin elements 1900 but for the interfaceterminals as well (not shown).

Referring now to FIG. 22, an exemplary embodiment of a dual hingedbobbin assembly 2200 is shown and described in detail. Specifically,while many of the previous hinged embodiments shown only included ahinged coupling on one side of the coil device (i.e., on the innerdiameter portion of the bobbin elements), the hinged bobbin assembly ofFIG. 22 utilizes hinged portions that occur on opposite portions of thebobbin element. Specifically, the central bobbin element 2250illustrated has both an inner hinged coupling 2220 as well as an outerhinged coupling 2240. The use of such an arrangement allows for theRogowski coil devices to be arranged into more complex geometries otherthen the circular or oval-type geometries discussed previously herein.See, for example, the “zigzag” bobbin arrangement of FIG. 24, which canbenefit from the flexibility attained via the use of a dual hingedbobbin assembly. In an exemplary implementation, each of the bobbinelements will be universal in nature such that each bobbin element isstructurally identical so as to enable the production of bobbin elementsfrom a single tool. The assembler will then arrange these bobbinelements into an assembly by choosing whether or not a given bobbinelement should use the inner hinged coupling, the outer hinged couplingor a combination of the two, as is the case with the central bobbinelement illustrated in FIG. 22. Alternatively, multiple tools and bobbinelement designs can be used to achieve a desired geometry. For example,separate bobbin elements can be created for: (1) inner hinged coupledbobbin elements; (2) outer hinged coupled bobbin elements; and (3)dual-hinged coupled bobbin elements.

Referring now to FIGS. 23A and 23B, parallel pairs of so-called “zigzag”bobbin arrangements are shown and described in detail. It is appreciatedthat the term “zigzag” as used in the present context merely connotesand alternating pattern (which may alternate regularly or irregularly),and in now way is limited to the illustrated shapes or sizes orconfigurations.

FIG. 23A illustrates four (4) bobbin elements 2300 arranged about a busbar 2350 with a rectangular cross section, although other bus bargeometries (e.g. square, round, etc.) could readily be accommodated.These four (4) bobbin elements are each arranged in pairs 2320 in theillustrated embodiment, and are coupled via their respective innerhinged coupling 2330. In this fashion, the hinged coupling is positionedfurther away from the bus bar then the ends 2332 of the unhingedportions of each of the bobbin elements.

FIG. 23B illustrates an opposite arrangement, where the paired up bobbinelements 2320 are coupled via their respective outer hinged coupling2360 thereby positioning the hinge away from the bus bar 2350.

FIG. 24 illustrates one exemplary implementation of the zigzag bobbinarrangements illustrated in FIGS. 23A and 23B, as they are arrangedabout a rectangular bus bar 2450. Specifically, FIG. 24 included twopairs of bobbin elements 2410 that are connected via their outer hingedcoupling 2412; i.e., those pairs of bobbin elements arranged along thelength dimension of the bus bar 2450, while the bobbin element pairs2420 arranged at the ends of the bus bar are connected via their innerhinged coupling 2422. Additionally, the bobbin element pairs arranged atthe ends of the bus bar are connected to the two pairs of bobbinelements arranged along the length dimension of the bus bar via theirrespective inner hinged couplings 2422. Each of these bobbin elementsare further arranged within a housing 2460 that includes a number ofalignment features 2470 that are in this embodiment directly molded intothe housing itself. These alignment features maintain the bobbinelements in their desired positions such that the angular relationshipsbetween adjacent bobbin elements are advantageously maintained in adesired and repeatable relationship which provides, inter alia,consistency of manufacture and performance.

FIG. 25A illustrates an alternative current sensing device 2550 that canbe utilized with multiple ones of the bobbin elements described herein.While many of the current sensing device embodiments discussed hereinuse closed loops, the embodiment of FIG. 25A uses a non-closed loopconfiguration. Specifically, the bobbin elements 2500 are arranged suchthat the start and finish bobbin elements do not actually complete athree hundred-sixty (360) degree loop around the conductor(s) 2560 to besensed. Such a configuration is particularly useful, inter alia, whereit is desirable to measure the current in the conductor withoutnecessarily having to either: (1) thread the conductor through thecenter of the Rogowski device; or (2) disassemble and reassembly theRogowski device around the conductor to be measured. FIG. 25Billustrates an alternative arrangement for a non-closed loop.

Referring now to FIG. 26, a current sensing device 2600 with anintegrated bus bar 2660 is shown and described in detail. Specifically,the current sensing device of FIG. 26 includes a housing 2610 thatincorporates a plurality of segmented bobbin elements (not shown), suchas those elements described previously herein. However, the currentsensing device of FIG. 26 includes an integrated conductor 2660 thatpasses through the center portion of the underlying device thatinterfaces with the current source to be measured. In one embodiment,the integrated conductor interface interfaces with a socket connectorsuch that when the current sensing device with integrated bus bar isplugged into these socket connectors, current is able to pass from thetransmission side of a power distribution system to the load side of thepower distribution system (e.g. a consumer's home). In an alternativeconfiguration, the integrated bus bar is electrically connected to aprinted circuit board that acts as the interface between thetransmission side of the power distribution system and the load side ofthat same system. In this manner, the current sensing device withintegrated bus bar acts as a modular current sensing device thatconnects/plugs into the interface between the load and transmission sideof a power distribution system so as to enable current measurement ofpower delivered to the load side of the power distribution system.Current sensing terminals 2620 are also illustrated which provide thenecessary signal information for measuring the current passing throughthe integrated bus bar.

FIG. 27A illustrates a finished package option that, in the illustratedembodiment, includes a number of surface mounted terminals 2720integrated onto the housing 2710 of the device 2700. These surfacemounted terminals act as an interface to the underlying currentmeasuring circuitry of the device. FIG. 27B illustrates this finishedpackage option assembly 2750 mounted to a printed circuit board. Thisfinished package option is also mounted over, or has a conductor to bemeasured passed through, the central aperture 2712 of the device. Inthis fashion the finished package option illustrated can easily beintegrated into interface equipment used to record and/or distributecurrent sensing measurements obtained from the underlying circuitry ofthe device. Moreover, while surface mounted terminals are illustrated inthe embodiments of FIGS. 27A and 27B, it is appreciated that thesesurface mounted terminals can be substituted with other terminal typessuch as through-hole terminations that are connected via a pluggableconnector and/or a eutectic solder connection to a through-hole via on aprinted circuit board. In addition, while the surface mounted terminalsare illustrated as self-leaded terminals, it is appreciated that insertmolded or post-inserted metallic surface mounted terminals could beutilized as well in place of the self-leaded terminals shown.

Referring now to FIG. 28, a multiple sensor device 2800 with built-incross talk compensation is shown and described in detail. In theillustrated embodiment, the multiple sensor device includes three (3)non-closed loop configuration current sensing devices 2850. Furthermore,while non-closed loop configurations are shown, it is appreciated thatclosed loop configurations, such as those described herein, may bereadily substituted in the multiple sensor device of FIG. 28. Themultiple sensor modules are preferably housed within a single housing2810.

In one embodiment, the multiple sensor module is of the integrated busbar-type discussed previously herein with regards to FIG. 26. In analternative embodiment, the multiple sensor module constitutes afinished package options such as that discussed with respect to FIGS.27A and 27B. In an exemplary implementation, the multiple sensor modulewill include shielding (not shown) between adjacent ones of the sensormeasuring circuitry in order to prevent crosstalk interference betweenadjacent conductors to be measured. In an exemplary application, themultiple sensor device 2800 is utilized in multiple conductorapplications where there are multiple conductors that need to bemeasured.

Alternative Winding Configurations—

Referring now to FIGS. 29A-30, various embodiments for alternativewinding configurations for use with, for example, the segmented bobbinelements described herein are shown and described in detail. As shown inFIG. 29A, an exemplary center start/center finish winding technique 2900is illustrated. Such a configuration has been shown, in some windingimplementations, to reduce the noise error seen with high voltages inRogowski device implementations. In the illustrated example, the sensorwinding begins at the center of the assembly, as opposed to the end ofthe assembly as is described at, for example, FIGS. 18A-18S infra. Thesensor winding begins at a winding terminal 2910 (for example, astarting end clip 1890 type winding terminal illustrated in FIG. 18Adescribed subsequently herein). The winding, in the illustratedembodiment, traverses the bobbin elements as illustrated at 2902 (i.e.,the first through fourth layers illustrated traverse along bobbinelements three, two, one, one, two, three, four, five, six, five, andfour). Upon completion of the winding operation for the four layersillustrated, the sensor winding is terminated at winding terminal 2920.The shielding layer is then wound starting at terminal 2930 where ittraverses in the opposite direction of the sensor winding (i.e., alongbobbin elements four, five, six, six, five, four, three, two, one, two,three). In this manner, a segmented bobbin Rogowski device can be woundfrom a center portion of the assembly, as opposed to the ends.

It will be appreciated that while shown with six (6) segmented bobbinelements, any number of bobbin elements can be utilized consistent withthe principles of embodiments of the present invention. Moreover, whilethe sensor winding and shield windings are illustrated starting andfinishing at the center of the assembly, it is appreciated that it maybe desirable in some instances to start away from the geometricalcenter. For example, the sensor and shield windings can start betweenbobbin elements two and three, as opposed to between elements three andfour as shown. Additionally, while the sensor and shield windings areshown originating in the same general location, it is appreciated thatthis doesn't necessarily have to be the case, i.e. the sensor windingscould originate between bobbin elements three and four, while the shieldwindings could originate between elements four and five. These and othervariations would be apparent to one of ordinary skill given the presentdisclosure.

Referring now to FIG. 29B, yet another alternative configuration isshown which can be utilized, for example, in the embodiment illustratedin FIG. 29A. In a first implementation discussed in the context of FIG.29A (i.e., a four layer sensor winding embodiment), the first two layersare wound in a first direction (e.g., clockwise), with the twosubsequent sensor winding layers being wound in a second, oppositedirection (e.g. counter clockwise). Such a configuration reduces theeffects of interwinding capacitance seen in the sensor assembly.

As an alternative implementation, and in the context of FIG. 29A, thesensor winding process begins at the start termination 2910 where ittraverses bobbin elements one through six to complete layer one and back2960 to bobbin element one to complete layer two in a first windingdirection (e.g. clockwise). Upon reaching the bobbin element one, thesensor winding is traversed across bobbin elements one through six andback to one in a second winding direction (e.g. counter clockwise) tocomplete layers three and four.

Referring now to FIG. 30, a bank winding configuration 3000 is shown anddescribed in detail. Specifically, FIG. 30 illustrates a windingtechnique for a single bobbin element 3002. The winding techniqueutilizes so called winding banks 3040, 3050, 3060 that each includemultiple layers (i.e., first layer 3010, second layer 3020, and thirdlayer 3030). Each winding bank in the illustrated embodiment reduces thenumber of windings as the winding process progresses from the firstlayer to the third layer. Such a winding configuration reduces theamount of inter-winding capacitance seen on the device, therebyimproving the electrical performance over a given electricalcharacteristic (e.g., frequency) range.

While the bank winding configuration illustrated includes three (3)distinct winding banks, it is appreciated that more or less windingbanks could be readily substituted for the three that are illustrated.Moreover, while three layers of windings are shown for each windingbank, it is appreciated that more or less winding layers could also beutilized depending on the performance requirements of the device.Furthermore, while each winding bank is shown with a “stepped” number ofwindings per layer, it is appreciated that certain embodiments mayutilize winding banks with an equal amount of turns per layer. These andother alternatives would be readily apparent to one of ordinary skillgiven the present disclosure.

Alternative Shielding Configurations—

Referring now to FIGS. 31-34B, various shielding configurations for usein the current sensing devices described herein are shown and describedin detail. Various embodiments described herein consist of one or moresensor winding layers (i.e., a layer of winding that is utilized tosense current in a Rogowski type device) along with one or more layersof shielding that are used to improve the performance of the device bymitigating the deleterious effects of electromagnetic radiation. In atypical context, both the winding and shielding layers are formed froman insulated winding; i.e., a conductive wire with an insulating coatingdisposed over the conductive portion. However, it is recognized that insome embodiments, it may be advantageous to remove the insulating layersof the shielding layer so that the shielding layer consists ofnon-insulated windings. These and other variations should be consideredas readily available alternatives for the various embodiments describedherein.

Referring now to FIG. 31, a first shielding configuration for use on acurrent sensing device 3100 which utilizes alternating direction shieldwindings is described. In the embodiment illustrated, the first bobbinsegment has a shielding layer wound in a first direction 3110 (e.g.counter clockwise), while a second bobbin element has a shielding layerwound in a second direction 3120 (e.g. clockwise). The alternatingshielding layers are repeated throughout the remaining bobbin elementssuch that the first, third and fifth bobbin elements are each wound inthe same direction 3110, 3130 and 3150. Moreover, the second, fourth andsixth bobbin elements are each wound in the same direction 3120, 3140,3160.

While the illustrated embodiment of FIG. 31 shows the winding directionof the shielding layer alternating from bobbin element to bobbinelement, it is appreciated that it may be desirable in some instances toalternate winding directions for the shielding layer(s) every two ormore bobbin segments. For example, in the context of the centerstart/center finish winding technique illustrated in FIG. 29A, theshielding layer can, in one embodiment, be wound in a first directionwith respect to bobbin elements one through three, while bobbin elementsfour through six have a shielding layer that is wound in an oppositedirection. Moreover, where a given bobbin element has two or more layersof shielded windings, each layer can be alternately wound (i.e. a firstlayer wound in a first direction and a second layer wound in a second,opposite direction).

Referring now to FIG. 32, an exemplary interleaved shielded windingconfiguration 3200 is shown and described in detail. FIG. 32 illustratesa cross sectional view of a wound bobbin element 3202, with windinglayers originating at one or more terminal posts 3204. The configurationillustrated shows three (3) layers of windings; i.e., first layer 3210,second layer 3220 and third layer 3230. Four (4) or more layers could bealso be used. In the embodiment illustrated, the shielding layers areinterleaved with the sensor winding layers. For example, layers 3210 and3220 consist of shielding layers, while layer 3230 is made up of asensor winding layer. In the context of a four (4) layer embodiment,with the fourth layer disposed atop the top layer 3210, the fourth layerand layer 3230 could be shielding layers, while layers 3210, 3220consist of sensor winding layers. These and other interleavedembodiments would be readily apparent to one of ordinary skill given thepresent disclosure.

FIG. 33 illustrates yet another alternative shielding configuration.Specifically, FIG. 33 illustrates a bobbin element assembly 3300 (here adual hinge coupled bobbin assembly is shown although other assembliesdescribed herein could readily be substituted). Each wound bobbinelement 3310 includes a shielding layer 3320 disposed over the sensorwindings. In one exemplary implementation, the shielding layer comprisesa copper foil that is cut to a predetermined width so as to fit withinthe winding channel of the bobbin 3310. Alternatively, the copper foilcan be substituted with a copper mesh that is arranged so as to bedisposed over the sensor windings of the assembly, or yet other types ofshielding materials and/or configurations may be used.

Referring now to FIG. 34, yet another shielding configuration isillustrated in the context of a Rogowski device 3400 that utilizes anintegrated housing 3420. In the illustrated embodiment, a copper (orother appropriate shielding material) layer 3410 is disposed along thecentral aperture 3402 of the housing.

Exemplary Current Sensing Apparatus Applications—

The exemplary current sensing apparatus described herein can be used inany large number of applications, and/or where it is desirable tomeasure the current of a conductor without otherwise disturbing thecurrent carrying conductor its elf. One such common application is inthe incorporation of current sensing apparatus in electrical meters foruse in residential, commercial and industrial applications. By measuringthe current being consumed by a consumer of electricity, and passingthis information along to the utility company via a network interface onthe meter, the utility company or other entity can better gauge what tocharge its consumers, and/or better understand the energy being consumedthroughout various parts of an electricity grid or system.

As well as being resistant to tampering and electromagneticinterference, current sensing apparatus such as Rogowski coils have wideapplicability to various applications included in the recent pushtowards so-called smart grids. Furthermore, in addition to beingutilized in power distribution metering applications (such as circuitbreakers, residential and industrial monitoring stations, etc.), the useof current sensing apparatus in a wide variety of appliance applicationswhich utilize large amounts of current (such as for example, electricwelders and motor controls) are envisioned as well.

Multi-Coil Current Sensing Apparatus—

Referring now to FIG. 15A, a first exemplary embodiment of a multi-coilRogowski coil device is illustrated. Specifically, the multi-coilRogowski coil device of FIG. 15A comprises two (2) Rogowski coil devicesof the type previously illustrated with respect to FIG. 1 above,disposed in a “stacked” or juxtaposed arrangement. While illustratedwith the coil embodiment of FIG. 1, it is appreciated that any of thecurrent sensing apparatus embodiments described herein could readily bestacked in such a manner (including without limitation the free-space orbobbin-less embodiments described elsewhere herein). Furthermore, theupper and lower Rogowski coil devices are each shown with only a singlecoil element or segment 1510 and 1520, respectively. It should berecognized however that in practice, each of the Rogowski coil devicesof the illustrated embodiment would have eight (8) wound coils; thesingle wound coil is illustrated FIG. 15A merely so as to more easilyillustrate the relative offset between the top and bottom Rogowski coildevices.

Recall from the previous discussion of prior art Rogowski coil devices,that these prior art devices are uniform in their distribution of theirwindings (i.e. they are non-segmented). Furthermore, as the Rogowskicoil devices 100 illustrated in FIG. 15A are segmented, there isexpected to be some flux leakage or “imperfection” in the gaps betweenthe wound coils of these devices. Accordingly, by stacking the Rogowskicoil devices in FIG. 15A in proximity to one another, and angularlyoffsetting the top segmented wound coil 1510 from the bottom segmentedwound coil 1520 (and combining the outputs from the two coils), thecombined devices behave more like an ideal Rogowski coil with anon-segmented uniform distribution of windings.

It will be appreciated that while only two coils are shown in theembodiment of FIG. 15A, three (or more) coils can be stacked in such amanner if desired. For example, it may be desirable to utilize three (3)such coils in stacked arrangement (not shown), with the gaps betweensegments in the middle coil corresponding to coil segments of both theupper and lower coils, such that the flux leakage from the middle coilgaps is addressed substantially symmetrically (from both top and bottom)by the upper and lower coils, respectively.

In another configuration (such as where the gaps are appreciable in sizerelative to the length of the coil segments), the placement of the coilsof the respective stacked coils can be “phased” with respect to the gapof the first; e.g., a first coil at vertical position zero (0) at anangular position zero (0), the second coil at vertical position one (1)atop the first coil at angular position zero plus x, the third coil atvertical position two (2) atop the second coil at angular position zeroplus y (where y is greater than x), and so forth.

Generally speaking, for any appreciable affect on leakage or precisionto occur due to the addition of more coils, the coils must be offsetfrom one another in azimuth somewhat (i.e., segments of one coil overlapwith gaps in another coil); however, this is not always the case. Atleast some effect on precision/leakage may be achieved in certainconfigurations simply by stacking two or more coils with their segmentsaligned, due to the fact the leakage from the gap of one coil coupleswith the adjacent segments of the other coil(s) even when the adjacentsegments of the second coil are not aligned with the gaps.

FIG. 15B illustrates a top down view of the two Rogowski coil devices ofFIG. 15A. Specifically, the angular offset can be clearly seen in FIG.15B with the bottom wound coils 1520 offset or shifted with respect tothe top wound coils 1510. While the stacked Rogowski coil device ofFIGS. 15A and 15B illustrate only two (2) such devices, it is recognizedthat three (3) or more Rogowski coil devices can also be stacked withtheir outputs combined and angularly offset from one another in order toprovide a more ideal behavior when measuring current passing through aconductor to be measured.

FIG. 15C illustrates another embodiment of a stacked Rogowski coilapparatus. Specifically, FIG. 15C illustrates a variant to the apparatusshown in FIG. 15A in which tuning covers 1530 are placed about theRogowski coil devices 100. These covers 1530 are preferably made from amolded polymer and have features (not shown) which permit the covers torotate with respect to one another while coupled. As the two devices arepermitted to rotate 1534, a user can effectively tune the output of thestacked Rogowski coil devices in order to optimize the performance ofthe stacked Rogowski coil device. The tuning covers also include a hinge1532 which permits the covers and the Rogowski coil devices to bepositioned about the conductor to be measured without necessitating thatthe conductor be threaded through the central aperture 1536.

Referring now to FIG. 15D, an alternative tunable stacked Rogowski coilapparatus 1540 is shown and described in detail. The apparatus of FIG.15D includes three (3) Rogowski coil devices 100; although the middledevice has been removed from view in order to better illustrate theinner workings of the stacked apparatus 1540. The Rogowski coil devices100 are received within a protective cover 1560 which is illustrated incross section. The devices 100 are similar in construction to thosedevices shown in FIG. 1; however they have been, in an exemplaryembodiment, constructed from a laser direct sintering (LDS) polymermaterial. Each of the devices have formed thereon two (2) conductivelyplated surfaces 1540 which are electrically coupled to respective endsof the Rogowski coil segmented windings. The Rogowski coil devices 100are received within a channel 1550 formed within the protective cover1560. These channels 1550 act as a guide which permits the Rogowski coildevices 100 to rotate within the cover 1560.

The cover 1560 is also preferably formed from an LDS polymer materialthereby permitting the channels 1550 to be conductively plated as well.Accordingly, the conductive channels 1550 of the cover are electricallycoupled to the conductive pads 1548 of the Rogowski coil devices.Various interfaces (including LDS polymer interfaces) between theindividual devices 100 and the cover 1560 can be utilized such as thosedescribed in co-owned and co-pending U.S. patent application Ser. No.12/482,371 filed Jun. 10, 2009 and entitled “Miniaturized Connectors andMethods”, the contents of which are incorporated herein by reference inits entirety. The conductive channels 1550 are then electrically coupledto one another and also to output terminals 1562. These output terminals1562 can then either be attached to external conductors (not shown) oralternatively mounted as either a through hole or surface mount contactto an external substrate (not shown).

As an alternative to the use of LDS polymers, the Rogowski coil devices100 and cover 1560 could also be constructed as a composite structure.Specifically, the conductive pads 1548 on the Rogowski coil device andthe conductive channels 1550 is constructed from a metallic alloy placedonto the underlying polymer structures. These metallic alloys can eitherbe insert-molded or post inserted into pre-formed apertures present onthe cover and Rogowski coil header, respectively. In addition, thesemetallic alloys are preferably shaped so as to act as a spring andprovide additional contact force while the Rogowski coil devices 100 arerotated within the cover. The Rogowski coil devices are rotated withinthe cover via a protrusion 1566 through an aperture 1564 located on thecover 1560. By manipulating the protrusion 1566 in a lateral (azimuth)direction 1568, the individual Rogowski coil devices can be tuned withinthe assembly 1540.

Referring now to FIG. 15E, a concentrically arranged stacked Rogowskicoil apparatus 1570 is shown and described in detail. Specifically, thestacked Rogowski coil apparatus 1570 comprises an inner Rogowski coil1580 and an outer Rogowski coil 1575. Both the inner and outer Rogowskicoils are adapted to rotate in a circumferential direction 1572 withrespect to one another. Similar to the stacked concepts illustrated inFIGS. 15A-15D, the concentrically stacked Rogowski coil apparatus ofFIG. 15E permits the windings 1577 of the outer coil 1575 to bepositioned adjacent the unoccupied intermediate segments 1582 of theinner coil 1580. Similarly, the windings 1584 of the inner coil 1584 arepositioned adjacent the unoccupied intermediate segments 1579 of theouter coil 1575. The respective ends of the inner and outer Rogowskicoil devices are then electrically coupled to one another to provide acombined output for a conductor to be measured.

In yet another exemplary embodiment two (2) or more of theseconcentrically arranged stacked Rogowski coil apparatus 1570 can beplaced in a top-to-bottom disposition (similar to that shown withrespect to FIG. 15A), thereby adding yet another layer of redundancy tohelp correct against distortions in electrical performance due to thesegmenting of the coils. In such a configuration it is desirable thatthe winding portions 1584 of the inner coil be placed adjacent to theunoccupied intermediate segments 1582 of the adjacent inner coil, whilethe winding portions 1577 of the outer coil are placed adjacent theunoccupied intermediate segments 1579 of the adjacent outer coil.

In another variant, a “hybrid” stacked/concentric configuration (notshown) is provided. In this variant, the individual coils of themulti-coil assembly are of different radius, yet not so that one fitsentirely within the other (i.e., the outer diameter of one coil is suchthat it is greater than the inner “hole” diameter of the next adjacentcoil, such that they sit in a stacked configuration, but with the coilshaving different diameters. The variation of the coil diameter as afunction of vertical position may be progressive (e.g., diameter of coilat vertical position zero (0) being smaller than that of the next highercoil, and the diameter of that next higher coil being smaller than thatof the third coil above it, and so forth), or assume other patterns(such as an “hourglass”, wherein the lowest coil is of a larger diameterthan the (second) coil directly above it, and the coil directly abovethat second coil is also of a/the larger diameter).

Furthermore, while primarily envisioned as tunable embodiments, thestacked Rogowski coil devices of FIGS. 15A-15E are not so limited. Infact, it may be desirable in some embodiments to maintain a fixedrelationship between adjacent ones of Rogowski coil devices therebysimplifying the assembly.

It will also be appreciated that in yet another embodiment, the verticalspacing or disposition of the different coils (whether in “stacked” or“concentric” configuration) can be varied, thereby increasing/decreasingthe coupling or interaction of the coils. For instance, the verticalheight between tow stacked coils can range from zero (0) to literallyany value consistent with the form factor of the application. Obviously,the most coupling effect will be achieved when the coils are immediatelyproximate one another, but it is contemplated by the present inventionthat “tuning” of the assembly may also comprise variation of thevertical spacing of coils in the stacked or concentric configurations.In one variant, such variable spacing is accomplished by simplysubstituting non-conductive spacers (e.g., flat toroids or “washers” ofprescribed thickness made from e.g., a polymer, paper, kapton, etc.)between the individual coils. In another variant, the case whichcontains the coils may be configured so that the stacked coils mayreside at different elevations relative to one another. Myriad othertechniques for allowing variation of the spacing between coils will beappreciated by those of ordinary skill when given the presentdisclosure.

It is also noted that while the aforementioned embodiments of stackedand concentric (and hybrid) coil assemblies may be “tuned” by varyingthe placement of the coils relative to one another—whether vertically,horizontally, or in azimuth or even attitude (yaw)—they may also betuned to achieve the desired level of performance by virtue of theirconstituency. For example, in one embodiment of the assembly, theuser/installer is provided with a plurality (e.g., two or more) of verylow cost, lower-precision coils. These coils each may for example onlyhave a few number of segments, relatively large spacing betweensegments, and/or less turn density in each segment, such that they are amore gross approximation of the “perfect” Rogowski coil (yet are alsovery inexpensive to manufacture). It may be that one user of theassembly merely requires a low-precision, gross approximation of thesensed parameter(s) (e.g., current through a conductor), and hence theuse of a single one of the aforementioned coils within the assembly maysuffice for these purposes. Alternatively, another user of the assemblymay require much higher levels of precision in their intendedapplication; such levels of precision cannot be achieved through use ofone of the low precision coils alone, yet can be achieved with perhapstwo or three coils used in stacked/concentric/hybrid configuration. Inthis fashion, one embodiment of the invention is configured such thatcoils can be added or subtracted by the user as required in order toachieve their desired level of precision, while also achieving the mosteconomical implementation (in contrast to a “one-size-fits all” approachof the prior art, wherein the device precision/accuracy is effectivelyfixed).

The foregoing methodology may also be applied in installations wherelarge numbers of individual or aggregated coils may be required, such asby a utility implementing a customer-wide monitoring program. Forexample, where the installed electrical meter base for the utility'scustomers is substantially homogeneous, the utility can “tune” thedevice installation on an exemplary or representative meter, and thensimply replicate that installation on all other meters within thecustomer base (without having to individually tune each one). Hence, theutility can purchase one “tuning kit”, which may for example have myriaddifferent types, diameters, winding densities, segment spacings, andconfigurations of coils/coil assemblies, and tune the prototype orrepresentative installation so as to optimize performance and/or cost(i.e., achieve the desired level of precision at the lowest possiblecost). Once the optimal configuration (or configurations for respectivetypes of customer installations) is/are known, the utility can thensimple purchase the cost/performance-optimized configuration en massefrom a supplier, thereby obviating the waste and cost of “leftover” orunused parts (e.g., coils) that would result from purchasing a multitudeof individual tuning kits.

It is also noted that while some of the foregoing embodimentscontemplate the use of homogeneous coil configurations (e.g., two orthree substantially identical coils used in a stacked arrangement), thepresent invention further contemplates the use of heterogeneous coilconfigurations. For instance, in the stacked assembly described above,the first coil might have a certain segment winding density and segmentspacing/number of segments. The second coil, however, might utilize adifferent density/spacing/number, albeit having the same effectiveradius and/or vertical height. Moreover, as noted previously, the coilsmay also (or alternatively) have different coil heights and/or radii,different cross-sectional profiles, etc. Hence, an assembly which can“mix and match” different coil types is contemplated herein. For such anassembly, the housing (if any) may also be configured to accept thedifferent coil types, so as to obviate the user/installer having toprocure a different housing type depending on the selectedcombinations/configuration of component coils. This “universal” housingcan readily be constructed so as to accommodate the various possibleconfigurations, yet meet the aims of relative conservation of space, lowcost, holding the coil(s) in a desired orientation relative to themonitored conductor(s), and so forth.

FIG. 35A illustrates a substrate assembly embodiment 3500 that utilizesthree different printed circuit boards. Specifically, the embodiment ofFIG. 35A includes an upper substrate 3510, a lower substrate 3512 and amiddle substrate 3514. Disposed between these substrates are a number ofbobbin elements 3520 which collectively form a multi-coil Rogowski coildevice. In one embodiment, the multi-coil Rogowski coil device of FIG.35A comprises two (2) Rogowski coil devices of the type previouslyillustrated with respect to FIGS. 19A-19C above, disposed in a “stacked”or juxtaposed arrangement. However, other embodiments, such as thoseillustrated in FIG. 20A, can be readily substituted or even intermixed(as to the different layers).

Note that as the Rogowski coil devices illustrated in FIG. 35A aresegmented in nature, there is expected to be some flux leakage or“imperfection” in the gaps between the wound coils of these devices forthat reason. Accordingly, by stacking the Rogowski coil devices in FIG.35A, the combined devices behave more like an ideal Rogowski coil with anon-segmented uniform distribution of windings. While the two Rogowskicoil devices in FIG. 35A are illustrated with their respective bobbinelements aligned, it is recognized that the bobbin elements of the topand bottom Rogowski coil device can be angularly offset from one anothersimilar in fashion as the embodiments discussed previously herein withrespect to FIGS. 15A-15E.

Furthermore, it will be appreciated that while only two coils are shownin the embodiment of FIG. 35A, three (or more) coils can be stacked insuch a manner if desired. For example, it may be desirable to utilizethree (3) such coils, with four (4) substrates in a stacked arrangement(not shown), with the gaps between segments in the middle coilcorresponding to coil segments of both the upper and lower coils, suchthat the flux leakage from the middle coil gaps is addressedsubstantially symmetrically (from both top and bottom) by the upper andlower coils, respectively. Alternatively, the placement of the bobbinelements of the respective stacked coils can be “phased” with respect tothe gaps of adjacent Rogowski coil devices as discussed previouslyherein.

Referring now to FIG. 35B, an alternative arrangement of the multi-coilRogowski coil device 3500 of FIG. 35A is shown and described in detail.Specifically, in the embodiment illustrated in FIG. 35B, the upper andlower substrates have been obviated in favor of the exclusive routing ofcircuitry on a centralized substrate 3530. In other words, each of theterminal locations for each of the bobbin elements of the upper andlower Rogowski coil devices is located on the central substrate. Theinterface circuitry to external processing circuitry (not shown) is thuslocated on a single substrate for both the upper and lower Rogowski coildevices.

In an exemplary implementation, the Rogowski coil devices are“combined”; i.e., the routing of the electrical circuitry betweenindividual bobbin elements alternates between the top and bottomRogowski coil devices as is best illustrated in FIG. 35C. In otherwords, the routing of the circuitry will go from a first bobbin element3550 on the lower Rogowski coil device to a first bobbin element 3552 onthe upper Rogowski coil device and back down to a second bobbin element3554 on the lower Rogowski coil device, and so on and so forth forbobbin elements 3556 and 3558, etc. Accordingly, the upper and lowerRogowski coil devices, and the respective circuitry on the circuitrylocated on the substrates, will act to create a single two-layeredRogowski coil device.

Methods of Manufacture for Current Sensing Apparatus—

Referring now to FIG. 10, a first exemplary method for manufacturing acurrent sensing apparatus 1000 is shown and described in detail.Specifically FIG. 10 illustrates the methodology for manufacturing thecurrent sensing apparatus illustrated in FIGS. 1-1B. At step 1010, thebobbin-less coils are wound on a mandrel. These coils can optionally bewound either one at a time or alternatively may be wound together so asto avoid having to interconnect them at a later processing step. Thesecoils may be wound either using a single layer of windings oralternatively in a multi-layer configuration. The wound coils are thenbonded together via the application of heat. The manufacture ofbobbin-less coils is described at, inter alia, co-owned U.S. patentapplication Ser. No. 11/203,042 filed Aug. 12, 2005 and entitled“Stacked Inductive Device and Methods of Manufacturing”, the contents ofwhich are incorporated herein by reference in its entirety.

At step 1020, the wound coils are threaded on a preformed return loop ofcopper wire (FIG. 1, 104). In an exemplary embodiment, the return loopof copper wire is formed so as to be generally “c-shaped” with arelatively small gap between the start and finish of the copper wirereturn loop.

At step 1030, each of the bobbin-less coils (FIG. 1, 102) are positionedwithin corresponding cavities (FIG. 1A, 112) of the segmented header(FIG. 1, 110).

At step 1040, the return loop of copper wire is snapped into thepositioning radial slot (FIG. 1B, 114) of the segmented header. In avariant, the return loop can be secured to the radial slot via the useof an epoxy adhesive.

At step 1050, the finish lead of the last wound coil is attached to anend of the return wire loop. This attachment may utilize any number ofknown techniques such as eutectic solder operations, sonic welding, andthe like.

At step 1060, the start lead of the first wound coil and the start ofthe return loop to the connection wires for the current sensingapparatus are connected. In an exemplary embodiment, the connectionwires comprise twisted pair, shielded lead wires.

At step 1070, the coil assembly is placed within or otherwiseencapsulated with a protective shell or coating thereby finishing theassembly. In an exemplary embodiment, the coil assembly is placed withinan over-lapping protective plastic clamshell case. The over-lappingnature of the plastic clamshell case provides enhanced protectionagainst resistance to high potential (also known as “Hi-Pot”) byincreasing the path length between the wires on the current sensingapparatus and the conductor to be monitored.

Referring now to FIG. 11, an alternative method for manufacturing acurrent sensing apparatus 1100 is shown and described in detail.Specifically FIG. 11 illustrates the methodology for manufacturing thecurrent sensing apparatus illustrated in for example FIGS. 2-2C; andFIGS. 4-4B. At step 1110, the segmented bobbin elements (FIG. 2, 210)are loaded onto a mandrel. In an exemplary embodiment, starting at oneend, each bobbin element is wound continuously over successive bobbinelements such that a continuous coil winding with no discreteinterconnections is included. These wound coils can be either single ormulti-layer in nature.

At step 1120, the return wire is threaded through respective apertures(FIG. 2A, 230) of the bobbin elements. In one embodiment, the returnwire comprises one or more twisted pair, shielded lead wires that arepre-stripped, separated and straightened so that they may be placedthrough the holes provided in the bobbin elements as they sit on themandrel. In an alternative embodiment, step 1120 is performed prior tobobbin winding at step 1110.

At step 1130, the wound bobbin elements are removed from the mandrel asa single assembly. The removed wound bobbin element assembly resemblespearls on a string.

At step 1140, the end wire of the last coil is terminated to one end ofthe twisted pair return wire. In embodiments which utilize two apertures(see e.g. FIG. 4, 432), the return wire can be routed back through thecenter portion of the segmented wound bobbin elements.

At step 1150, the bobbin elements are formed into their final shape(such as the exemplary torus-like or radial pattern described previouslyherein). In exemplary embodiments that include hinged couplings (e.g.FIG. 2, 220), the hinged couplings are positioned such that they are onthe inside diameter of the torus-like pattern.

At step 1160, each of the bobbin elements are placed withincorresponding cavities or slots associated with a plastic carrier. Forexample, in the illustrated embodiment of FIG. 4A, each bobbin element410 is placed within a respective cavity 464 of the external ring-likeheader 460.

At step 1170, the start lead of the first coil is terminated to theother end of the return wire loop.

At step 1180, the coil assembly is placed within or otherwiseencapsulated with a protective shell or coating thereby finishing theassembly such as that described with respect to step 1070 of FIG. 10previously discussed herein.

Referring now to FIG. 12, a third exemplary method for manufacturing acurrent sensing apparatus 1200 is shown and described in detail.Specifically FIG. 12 illustrates the methodology for manufacturing thecurrent sensing apparatus illustrated in FIGS. 3-3D. At step 1210, thesegmented bobbin elements (FIG. 3, 300) are loaded onto a mandrel. In anexemplary embodiment, starting at one end, the winding is anchored onone end and the wire is run along the top grooves (FIG. 3, 314) acrossall the bobbin elements. This wire is to be utilized as the return wire.

At step 1220, and starting on the far end (from the starting point ofthe return wire), the wire is wound back along the length of bobbinelements with windings placed on each bobbin element thereby making acontinuous coil winding with no interconnections while simultaneouslywrapping over the return wire. Similar to previous embodiments discussedabove, the coils can be either single or multi-layer depending on designconsiderations associated with the particular application for thecurrent sensing apparatus.

At step 1230, the wound bobbin elements are removed from the mandrel.

At step 1240, the bobbin elements are formed into their final shape(such as the exemplary torus-like or radial pattern described previouslyherein). With respect to the embodiment illustrated in FIGS. 3-3D, thereturn wire will now run along the outer diameter of the bobbinelements.

At step 1250, the finish lead and return wire are terminated toconductors associated with the connection wires (e.g. twisted pair,shielded lead wires).

At step 1260, the coil assembly is placed within or otherwiseencapsulated with a protective shell or otherwise encapsulated with acoating thereby finishing the assembly.

Referring now to FIG. 13, yet another embodiment for manufacturing acurrent sensing apparatus 1300 is shown and described in detail.Specifically FIG. 13 illustrates the methodology for manufacturing thecurrent sensing apparatus illustrated in for example FIGS. 5-5C. At step1310, the segmented bobbin elements (FIG. 5, 510) are loaded onto amandrel. In an exemplary embodiment, starting at one end each bobbinelement is wound continuously over successive bobbin elements such thata continuous coil winding with no discrete interconnections is included.These wound coils can be either single or multi-layer in nature.

At step 1320, the return wire is threaded through respective apertures(FIG. 5, 522) of the bobbin elements. In one embodiment, the return wirecomprises one or more twisted pair, shielded lead wires that arepre-stripped, separated and straightened so that they may be placedthrough the holes provided in the bobbin elements as they sit on themandrel. In an alternative embodiment, step 1320 is performed prior tobobbin winding at step 1310.

At step 1330, the wound bobbin elements are removed from the mandrel.The wound bobbin elements, because they are interconnected, are removedin a single assembly.

At step 1340, the end wire of the last coil is terminated to one end ofthe twisted pair return wire.

At step 1350, the bobbin elements are formed into their final shape(such as the exemplary torus-like or radial pattern described previouslyherein). In exemplary embodiments that include hinged couplings (e.g.FIG. 5B, 550), the hinged couplings are positioned such that they are onthe inside diameter of the torus-like pattern.

At step 1360, each of the bobbin elements are placed withincorresponding cavities or slots associated with a plastic carrier,similar to that shown in the illustrated embodiment of FIG. 4A.

At step 1370, the start lead of the first coil is terminated to theother end of the return wire loop.

At step 1380, the coil assembly is placed within or otherwiseencapsulated with a protective shell.

Referring now to FIG. 14, yet another method for manufacturing a currentsensing apparatus 1400 is shown and described in detail. SpecificallyFIG. 14 illustrates the methodology for manufacturing the currentsensing apparatus illustrated in, for example, FIGS. 6-6B. At step 1410,the segmented bobbin elements (FIG. 6, 610) are loaded onto a mandrel.The return wire is, starting at one end, routed in the cavity (FIG. 6,630) on the outer diameter of the bobbin element. Then, starting at theopposite end, each bobbin element is wound continuously over successivebobbin elements such that a continuous coil winding with no discreteinterconnections is included. These wound coils can be either single ormulti-layer in nature and are positioned over the return wire.

At step 1420, the wound bobbin elements are removed from the mandrel.The wound bobbin elements, because they are interconnected, are removedin a single attached assembly.

At step 1430, the end wire of the last coil is terminated to one end ofthe twisted pair return wire.

At step 1440, the bobbin elements are formed into their final shape(such as the exemplary torus-like or radial pattern described previouslyherein.

At step 1450, each of the bobbin elements are placed withincorresponding cavities or slots associated with a plastic carrier,similar to that shown in the illustrated embodiment of FIG. 4A. Inanother embodiment, each of the bobbin elements is placed within thebottom portion of an over-lapping clam shell case.

At step 1460, the start lead of the first coil is terminated to theother end of the return wire loop.

Finally at step 1470, the coil assembly is placed within or otherwiseencapsulated with a protective shell. In embodiments in which a plasticclam shell case is used, this step is accomplished by placing andsecuring the top over-lapping protective plastic clam shell case overthe assembly.

Referring now to FIGS. 18A-18S, one embodiment of the methodology forassembling an exemplary Rogowski coil device of the invention is shownin detail. FIG. 18A illustrates a first exemplary step in themanufacturing process. In FIG. 18A, the starting end clip 1890 isinserted within a respective aperture located on the starting end bobbinsegment 1810. The end clip 1890 is in one variant manufactured from aconductive sheet of metal, which is stamped and optionally plated so asto protect the surface finish of the clip. After insertion, the clip issubsequently bent. This bend 1891 is, in the illustrated example, formedat a 60-degree angle with respect to the non-bent portion of the clip1890. Alternatively, the starting end clip can be insert molded into thebobbin element during the injection molding process. In an exemplaryprocess, the clip is formed up away from the surface of the bobbinsegment by hand subsequent to insertion. Furthermore, exemplaryembodiments incorporate notches at the bend line of the end clip so asto reduce the force needed to perform the bend operation therebyreducing the possibility of cracking the bobbin segment during the bendoperation.

FIG. 18B illustrates the insertion of the finish end clip 1892 into thefinish end bobbin segment 1810. Note that the bobbin segments themselvesare identical between that shown in FIG. 18A and that shown in FIG. 18B(i.e. the start and end bobbin segments are identical with only theclips being different between the segments). Furthermore, also note thatthe “start” end clip of FIG. 18A and the “finish” end clip of FIG. 18Bare disposed on opposite ends of their respective bobbin segments. Thefinish end clip 1892 is also preferably not bent prior to insertion,such that the notched end of the end clip 1892 is positioned over thepass through conductor passageway 1893.

FIG. 18C illustrates the next step in the exemplary process, whereineach of the bobbin elements 1810 are loaded onto a winding mandrel 1870.The end clip bobbin element 1810 (i.e., the bobbin element discussedwith regards to FIG. 18B) is inserted onto the mandrel first, followedby six (6) bobbin elements that are devoid of any conductive clips.Finally, the starting bobbin element (i.e., the bobbin element discussedwith regards to FIG. 18A) is inserted on the end of the string of bobbinelements with the starting end clip 1890 facing away from the otherassembled bobbin elements.

Referring now to FIG. 18D, a polymer cord 1860 is slid into a groove1813 that is collectively formed by the assembly of bobbin elements1810. Note that the end of the cord is trimmed so that the end of thecord does not protrude past the outer wall 1811 of the end bobbinelement flange. In an exemplary embodiment, the cord is manufacturedfrom an electrical grade polytetraflouroethylene (PTFE). The diameterillustrated is 0.031 inches although it is recognized that other shapes(i.e. rectangular, polygonal, etc.) and sizes could be readily besubstituted in alternative designs. This cord is utilized to create aconnective “spine” that ultimately holds the assembly together in itsfinal form. While illustrated as using a PTFE cord, it is recognizedthat other items (such as tape, etc.) could also be readily substitutedin order to provide the so-called connective “spine” to the finishedRogowski coil device.

FIG. 18E illustrates the start of the winding process. Specifically, thewire 1862 to be wound onto the bobbin elements is first secured to thewinding pin 1872 of the mandrel and subsequently secured to the end clip1892. The conductive wire is, in the illustrated embodiment, wrappedaround the end clip 1892 twice prior to being routed into the bobbinelement winding barrel.

FIG. 18F illustrates the remainder of the end bobbin element 1810 beingwound with the required number of turns of wire 1862. In the illustratedexample, three (3) layers of wire are wound onto the bobbin element withfifty-two (52) turns of wire being wound in each layer. The layers areconstructed with the first layer being wound from left-to-right; thesecond layer being wound from right-to-left; and the third layer beingwound again from left-to-right, although other numbers of layers and/orlay patterns may be used consistent with the invention. For instance,all of the turns (e.g., 52 in this example) could be wound in a singlelayer in one direction. Alternatively, a two-layer back-and-forthpattern could be utilized.

FIG. 18G illustrates the routing of the wire 1862 from the newly woundend bobbin element to an adjacent bobbin element. Note that both bobbinelements shown include a transition feature 1863 comprised of aprotrusion that includes a curved edge. This curved edge helps preventdamage to the wire as it is routed between adjacent bobbin elements. Theadjacent bobbin element is then wound identically to that seen in FIG.18F (i.e. with three (3) layers comprised of fifty-two (52) turns each.The remaining bobbin elements 1810 are then similarly wound asillustrated in FIG. 18H.

FIG. 18I illustrates the end of the winding 1862 subsequent to beingrouted over each of the previously discussed bobbin elements, andsecured to the starting clip 1890. Similar to the end clip, the wire issecured to the starting clip by wrapping the wire around the start cliptwice, although other mechanisms may be used.

FIG. 18J illustrates the winding of the shielding layer 1864 onto thebobbin elements. As can be seen in FIG. 18J, the shielding layer iscomposed of an additional layer of fifty-two (52) turns that are woundin the opposite direction of the previously wound winding layers. Notealso that the wire that makes up the shielding wire is the same wirethat was used to previously wind the bobbin elements. The process iscontinued on as shown in FIG. 18K, with the remaining bobbin elementseach receiving a shielding layer. The use of the same wire that was usedin the previous windings is particularly advantageous from theperspective of manufacturing cost. As the bobbin elements are alreadydisposed onto a winding mandrel for the purposes of automating theplacement of the windings, no additional processing steps need to beperformed by an operator in order to wind the shielding layer onto thebobbin elements. Accordingly, the only additional costs added to thedevice by adding the shielding layer comes from the additional time thebobbin elements spend on the winding mandrel, which is minimal, alongwith the added material cost associated with the shielding layer whichis also minimal. Furthermore, it has been found that the use of the samewire 1862 for the shielding layer is just as effective at providingshielding for the device as other more labor intensive methods whichutilize copper foil, etc.

FIG. 18L illustrates how the wire 1862 is secured to the bobbin elementassembly. Specifically, FIG. 18L illustrates how the end of theshielding layer wire is secured at the end bobbin element. Essentially,a single turn of tape 1874 is wound onto the end bobbin element and theend of the wire 1862 is then routed over this single layer of tape andsubsequently secured by the additional wrapping of extra layers of tape.Both the excess wire 1862 and excess tape 1874 is then trimmed. Notethat the end of the shielding layer wire is not secured to the end clip1892.

Referring now to FIG. 18M, the wound bobbin elements are removed fromthe mandrel and the wire is secured to both the end clip 1892 and thestarting clip 1890 (not shown). The securing of the wire to these clipscan be accomplished in any number of differing ways. One implementationutilizes a resistance welding process to weld a portion 1866 of the wireto the respective clips. Alternatively, a eutectic soldering operationcould be used to physically and electrically secure the wire to therespective clips. Yet other methods will be recognized by those ofordinary skill given the present disclosure.

FIG. 18N illustrates the installation of the return wire 1850. Thereturn wire is inserted into the central passageway of the starting endbobbin element (i.e., the end with start clip 1890) and routed througheach of the bobbin elements until it meets the end clip element 1892 onthe end bobbin segment. This return wire 1850 is then subsequentlyelectrically secured to the end clip 1892 via a eutectic solderingoperation, resistance welding, etc. FIG. 18O illustrates that the finishwire 1852 is secured to the start clip 1890. Again this can beaccomplished by using e.g., either solder or resistance welding tosecure the finish wire to the start clip on the starting bobbin element.

FIG. 18P illustrates the insertion of the bobbin element assembly into ahousing 1880. The end bobbin element 1810 (i.e., the bobbin with tape1874 mounted thereon) is inserted into a respective cavity 1886 locatedon the housing first, and subsequent bobbin elements are inserted intotheir respective housing cavities around the ring-like shape of thehousing. Note also that the end bobbin element is disposed adjacent thefinish wire groove 1884 and return wire groove 1882 associated with thehousing.

FIG. 18Q illustrates the finish wire 1852 and return wire 1850 afterbeing inserted into their respective grooves of the housing. Note thatthe finish wire 1852 is disposed on top of the return wire in theillustrated embodiment which keeps the wires close together for thepurposes of mitigating unwanted external electrical interference.

Referring now to FIG. 18R, small drops of epoxy 1888 or another adhesiveis inserted into each of the cavities 1889 of the top housing 1883. Inaddition, a light bead of epoxy is also applied to the middle hole wall1887. The top housing 1883 is then mounted onto the housing 1880 asillustrated in FIG. 18S. The finish wire 1852 and return wire 1850 arethen twisted together in a clockwise direction for the purposes ofmitigating the effects of external electrical interference.

It will be recognized that while certain aspects of the invention aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of theinvention, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the invention disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the invention. Theforegoing description is of the best mode presently contemplated ofcarrying out the invention. This description is in no way meant to belimiting, but rather should be taken as illustrative of the generalprinciples of the invention. The scope of the invention should bedetermined with reference to the claims.

What is claimed is:
 1. A current sensing inductive device, comprising: aplurality of bobbin elements, each element having one or more terminalswith a conductive winding wound thereon; and a printed circuit boardwith an aperture existing therein; wherein said plurality of bobbinelements are disposed about said aperture and are electrically coupledto one another via said printed circuit board; and wherein at least twoof said plurality of bobbin elements are physically coupled to oneanother via a hinged coupling.
 2. The inductive device of claim 1,further comprising: a return conductor that electrically couples aleading one of said plurality of bobbin elements with a trailing one ofsaid bobbin elements.
 3. The inductive device of claim 1, wherein atleast three of said plurality of bobbin elements are physically coupledto one another via one or more of a plurality of hinged couplings,respectively, with a first hinged coupling disposed on a first side of awinding channel of a first bobbin element, and a second hinged couplingdisposed on a second side of said winding channel of said first bobbinelement.
 4. The inductive device of claim 1, wherein each of said bobbinelements comprises a pair of flanges with a winding spool disposedsubstantially therebetween, said conductive winding wound onto saidwinding spool.
 5. The inductive device of claim 4, wherein said one ormore terminals comprises self-leaded terminals incorporated into atleast a sidewall of at least one of said pair of flanges.
 6. Theinductive device of claim 1, wherein said plurality of bobbin elementscomprises three or more bobbin elements, with a start and a finishportion of said conductive winding being disposed on a non-end one ofsaid three or more bobbin elements.
 7. The inductive device of claim 1,wherein said conductive winding comprises a plurality layers disposed onone or more winding barrels of said bobbin elements.
 8. The inductivedevice of claim 7, wherein at least one of said layers comprises ashielding layer operative to at least mitigate electromagnetic noisetransmission during operation.
 9. The inductive device of claim 8,wherein said plurality of layers comprises: two or more shieldinglayers; and two or more current sensing layers; wherein said two or moreshielding layers and said two or more current sensing layers areinterleaved with one another.
 10. A current sensing inductive device,comprising: a plurality of linearly wound inductive elements, eachelement comprising: a pair of flanges; a winding channel disposedbetween said pair of flanges; a plurality of layers of conductivewinding disposed in said winding channel; and one or more hingefeatures; and a housing comprising a conductor receiving aperture;wherein said plurality of linearly wound inductive elements arecollectively disposed about said conductor receiving aperture in asubstantially alternating or zigzag fashion.
 11. The current sensinginductive device of claim 10, wherein at least one of said plurality oflayers of windings comprises a shielding layer.
 12. The current sensinginductive device of claim 11, wherein the direction of winding for saidshielding layer alternates between adjacently disposed linearly woundinductive devices.
 13. The current sensing inductive device of claim 10,wherein said conductor receiving aperture includes an integratedconductor that is to be sensed by said linearly wound inductiveelements.
 14. The current sensing inductive device of claim 10, whereinsaid housing further comprises a plurality of terminals for electricallyinterfacing with a printed circuit board.
 15. The current sensinginductive device of claim 10, wherein said housing includes a pluralityof alignment features that arrange said linearly wound inductiveelements in said substantially alternating or zigzag fashion when saidlinearly wound inductive elements are received therein.
 16. A currentsensing inductive device, comprising: a plurality of wound bobbinelements comprising a start and a finish bobbin element, the windings onthe plurality of wound bobbin elements configured such that the startand the finish bobbin elements form a non-closed loop around aconductor, each of the plurality of wound bobbin elements beingconnected via one or more hinge features to an adjacently disposed woundbobbin element.
 17. The current sensing inductive device of claim 16,further comprising: a plurality of the plurality of wound bobbinelements; and a housing, the housing containing the plurality of theplurality of wound bobbin elements.
 18. The current sensing inductivedevice of claim 17, further comprising a shielding element disposedbetween each of the plurality of the plurality of wound bobbin elements,the shielding element configured to prevent crosstalk interferencebetween a plurality of adjacently disposed conductors.
 19. The currentsensing inductive device of claim 16, wherein the conductor comprises anintegrated bus bar.
 20. The current sensing inductive device of claim19, wherein the integrated bus bar is configured to interface with asocket connector such that current is able to pass through theintegrated bus bar from a transmission side of a power distributionsystem to a load side of the power distribution system.
 21. The currentsensing inductive device of claim 19, wherein the integrated bus bar isconfigured to interface with a printed circuit board, the printedcircuit board configured to act as an interface between a transmissionside and a load side of a power distribution system.